Why would I ever cast True Strike?

Question

One of my players has complained several times that True Strike is a useless spell. The effect of True Strike is:

On your next turn, you gain advantage on your first attack roll against the target, provided that this spell hasn't ended.

His argument is that casting True Strike takes your action, preventing you from attacking, but attacking twice without advantage is better than attacking once with advantage, since you still roll twice but there's also the chance of hitting twice. This is obviously true, especially since you have to maintain concentration until your next turn to get any benefit out of the spell at all.

So why would you ever cast True Strike? Is it just a useless spell?

Answer 1

There are several reasons why you might want to cast True Strike. The first is that depending on your class, you might be able to get a bonus action attack after casting it, giving you one attack with advantage and one without, a definite improvement on two attacks without.

The second is that you might use it to overcome disadvantage:

• When you need a die result of 9 or higher to hit, a single normal attack becomes more likely to hit than 2 attacks with disadvantage, so it's worth the trade-off of using True Strike.
• When you need 8 or below, though, two attacks with disadvantage are more likely to hit, so just attack away without True Strike.

The third reason is that you might want advantage for something. For example, a Rogue might use True Strike to grant advantage to allow use of Sneak Attack.

Another reason is that you might know in advance that there was going to be combat, and cast True Strike for advantage on the first round. This would probably only happen when ambushing, but is still worth mentioning.

The final reason is that you might have an attack that you particularly wanted to hit. A Wizard using Plane Shift to send an enemy to the Abyss, for example, would want to be certain that the melee spell attack required would hit, otherwise they've wasted a high-level spell slot for nothing. Casting True Strike first would make it considerably less likely to miss.

Answer 2

Two Words: Arcane Trickster

TLDR: An Arcane Trickster build can get more damage by casting True Strike to trigger a Sneak Attack than by either attacking two rounds, using a damaging cantrip and then attacking, or casting a damaging cantrip both rounds. Also, certain feats can combine with True Strike to trigger Super Advantage (3d20) or even limited Ultra Advantage (4d20) on an attack roll.

Damage Comparison: True Strike vs Attacking

Because Rogues are restricted to using a Finesse Weapon to get their Sneak Attack damage, most make one their weapon of choice. Finesse Weapons (as presented in the PHB) all deal 1d8 or less damage as their base. For the purposes of this example, let's assume our Rogue is using a 1d8 Rapier and has a Dexterity modifier of +3, making their base weapon damage with a non-magical Rapier 1d8+3.

By the time this Rogue can become an Arcane Trickster at level 3, they get an additional 2d6 damage if they can Sneak Attack. If this Arcane Trickster takes True Strike as one of their cantrips, then, in the event that they do not have another condition that will give them an opportunity to use their Sneak Attack, they can potentially trade 2d8+6[14] (assuming 2 successful attacks, one on each turn) for 1d8+2d6+3[13] if neither roll is a critical hit, so they average out to be pretty similar. If either of your attacks is a critical hit, without True Strike granting you the Sneak Attack damage, the trade at level 3 is 3d8+6[18] vs 2d8+4d6+3[23] with it.

Tempted yet? I'm only getting warmed up.

As time goes by, this trade becomes better and better, eventually capping out at level 19 when it would be trading 2d8+6[14] for 1d8+10d6+3[37] without a critical hit and 3d8+6[18] without the spell vs a whopping 2d8+20d6+3[71] with the spell if one of the rolls is a crit!

Double critical hits are rare enough that it's not worth comparing.

Because it takes a while for the return to be worth it casting it often (whenever you can't gain Sneak Attack from another source) it may be best not to pick True Strike as one of your Cantrips at level 3, but the only other chance you will get is when you get your fourth and final Cantrip pick at level 10.

It is also good to take into account that a Rogue is also the most likely character to make an attack roll before initiative is actually rolled. If you attack from hiding, you already get Advantage, and therefore, Sneak Attack, but what if you are in a conversation and decide that someone needs to be stabbed? A Dexterity(Slight of Hand) skill check to hide the fact that you just cast True Strike (no verbal component) could be a great way to still get to open with a Sneak Attack. Depending on your DM, you could probably get Advantage on your attack just by a successful Dexterity(Slight of Hand) roll to conceal that you are readying a dagger, and which of the two checks would be harder will change from DM to DM as well, but using the Slight of Hand check for the spell may be a good way to get to use your rapier instead of a dagger.

Damage Comparison: True Strike vs Damaging Cantrips

The most common argument against True Strike I have seen compares casting a damaging Cantrip instead of attacking the first round, so let's look at that comparison as well, using our Arcane Trickster and the Fire Bolt spell (improves at levels 5, 11, and 17) as our damaging Cantrip.

$$ \begin{array}{r|r|l} \text{Level} & \text{Fire Bolt [avg. damage]} & \text{True Strike [avg. damage]} \\ \hline 3 & 1\text{d}10+1\text{d}8+3 \; [12] & 1\text{d}8+2\text{d}6+3 \; [13] \; \star \\ 5 & \star \; 2\text{d}10+1\text{d}8+3 \; [17] & 1\text{d}8+3\text{d}6+3 \; [16] \\ 7 & 2\text{d}10+1\text{d}8+3 \; [17] & 1\text{d}8+4\text{d}6+3 \; [19] \; \star \\ 9 & 2\text{d}10+1\text{d}8+3 \; [17] & 1\text{d}8+5\text{d}6+3 \; [22] \; \star \\ 11 & 3\text{d}10+1\text{d}8+3 \; [22] & 1\text{d}8+6\text{d}6+3 \; [25] \; \star \\ 13 & 3\text{d}10+1\text{d}8+3 \; [22] & 1\text{d}8+7\text{d}6+3 \; [29] \; \star \\ 15 & 3\text{d}10+1\text{d}8+3 \; [21] & 1\text{d}8+8\text{d}6+3 \; [31] \; \star \\ 17 & 4\text{d}10+1\text{d}8+3 \; [27] & 1\text{d}8+9\text{d}6+3 \; [34] \; \star \\ 19 & 4\text{d}10+1\text{d}8+3 \; [27] & 1\text{d}8+10\text{d}6+3 \; [37] \; \star \\ \end{array} \\ \text{(}\star\text{ marks larger damage source for that level)} $$

As you can see, the True Strike spell will often get more damage per round for a Rogue than the Fire Bolt spell, especially at higher levels, and that doesn't even account for doubling your Sneak Attack with a critical hit!

The fact that you could also crit with your damaging Cantrip is valid, however the comparison becomes difficult since if one of your attack rolls is a crit, you don't get to choose which one it is, so if it was the Fire Bolt roll you could get as much as 8d10+1d8+3[47] vs 2d8+20d6+3[71] with True Strike at level 19, but if the crit was the attack, then it would be 4d10+2d8+3[31]. In both cases the True Strike spell provides the superior damage output.

Finally, it is important to remember that your Arcane Trickster could also spam Fire Bolt both rounds instead of using a Rapier or other finesse weapon on one of the rounds, in which case, at level 19 the trade would be 8d10[40] vs 1d8+10d6+3[37] without a crit or 12d10[60] vs 2d8+20d6+3[71]. As you can see, in this scenario, the Fire Bolt spell is more competitive and when you should choose one over the other is really situational. Luckily, if they want to, an Arcane Trickster can have both of these spells at their disposal and make good use of each one.

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It's not all strawberry fields, however, since you still have to worry about the problems that come with delaying your attack a round: the enemy gets to act before taking damage, something could change that makes you not get to attack on your next turn, etc. Also, remember that this spell is only for those times when you can't get your Sneak Attack some other way, such as attacking together with a melee ally or the many other situations that grant Advantage. This spell is for those times when you are in a pinch and can't get your Sneak Attack any other way.

True Strike and Feats: Getting Super/Ultra Advantage

The first feat that you should take for this build is Lucky, unless your DM allows Xanathar's Guide, then your first pick should be Elven Accuracy (assuming you are an elf or half-elf).

Paraphrasing the The Elven Accuracy Feat from Xanathar's Guide:

Increase your Dexterity, Intelligence, Wisdom, or Charisma score by 1, to a maximum of 20

Whenever you have advantage on an attack roll using one of those ability scores, you can reroll one of the dice once

Be prepared for some DMs to veto Elven Accuracy though, because it essentially turns Advantage on all attack rolls into Super Advantage (best of 3 rolls) which will scare them.

As a DM, I would absolutely allow this feat, I don't believe it is over powered because it still requires Advantage, and sure, you can get Advantage more often with True Strike, but you also have to sacrifice an Action for that, so I feel like, rather than making it too overpowered, this feat brings True Strike up to the level it should have been on anyway.

If allowed, Elven Accuracy makes True Strike much better by not only increasing your chances to hit (57.81% chance to roll at least a 16) but also increasing your chances to get a critical hit (14.26% with best of 3d20 vs 9.75% with normal Advantage) and getting to double that Sneak Attack damage!

Add the Lucky feat to that and you will potentially get to roll as many as 4d20 on a single roll, granting what I call Ultra Advantage. Anyway, no matter what you call it, with this build, your two rolls over for two normal attacks can turn into 4 rolls for a single Sneak Attack.

With Ultra Advantage from one of your three uses of Lucky, your chances of rolling at least 16 are boosted to 68.36%, and your chances of rolling a 20 are 18.55%.

Again, I would argue that this is not overpowered because in the end, you can still only do this three times per day (and those uses of Lucky need to compete with things like Saving Throws), and only when you have Advantage, which you may have had to sacrifice an Action to set up for yourself. On top of that you are spending 2 Feats toward this build, so if your DM has an aneurism over it they need to chill out.

Answer 3

You should not cast it, ever

You should not even take this cantrip.

TL;DR: With disadvantage, do something that does not require an attack roll. Without, just attack.

Opportunity costs

By taking and using this cantrip you give up other, arguably better options, which you should also consider.

Concentration

True Strike requires concentration, meaning that using it interrupts or prohibits using other, more powerful spells from Faerie Fire through Haste and Evard's Black Tentacles to Dominate Monster.

Other Cantrips¹

A level 20 Sorcerer has only 6 cantrips, and any other class gets even fewer. If your options are Fire Bolt with or without True Strike, you are not as efficient against a Fire Elemental as if you had Fire Bolt and Toll the Dead.

Situations

I will check all the cases when you might use True Strike, and show that there are always better options.

Advantage

If you already have Advantage, True Strike is clearly worthless.

No Advantage, no Disadvantage

One attack with Advantage is worse than two without, unless you have Sneak Attack², so you should use both actions for attacking.

In both cases, you roll 2d20:

• If neither is high enough to hit, the result is the same
• If only one is high enough, the result is still the same
• If both would hit, 2 attacks do twice as much damage

Also Advantage is easy to get, most likely this is the reason no high level, powerful spells exist with an attack roll.³ In fact attack roll spells are so weak that you are better off using saving throw spells even if you had advantage.

Disadvantage

Mathematically there are situations where two attack rolls with Disadvantage are worse than one without. There are calculations in other answers when this might be the case.
These however fail to take into account the present value of the future attacks. Basically having 25% hit chance of doing 10 damage this round and 10 damage next round is more valuable than doing 10 damage next round with 50%. The target might be dead by that time, out of range⁴, your concentration on True Strike might be broken or a completely different spell needs to be cast urgently. It is hard to put a number on this, but depending on the situation it should be between 20% and 50% more valuable not to delay your activity.

In the comparison I will assume a base hit chance of 45% with Fire Bolt and 70% save chance with Toll the Dead (bad case, 1d8 damage)¹. The level does not matter, both cantrips improve at the same levels. In two rounds you have the following options:

• True Strike + Fire Bolt: 0.45 * 5.5 = 2.475 DPR
• Fire Bolt twice: 0.2025 * 5.5 * 2 = 2.2275 DPR
• Toll the Dead twice: 0.3 * 4.5 * 2 = 2.7 DPR

For a 4th level Wizard with Int 16, the enemy would have an AC of 17 , and a Wisdom save of 7. If the AC were lower, even the double Fire Bolts would outperform True Strike. If it were higher, save spells would outperform it by an even higher margin. And I did not even take into account the concentration and the discounting for present value.

Quantifying Concentration

On level 17 spending a 2nd level slot is quite cheap. See how Flaming Sphere⁵ + Fire Bolt compares to True Strike + Fire Bolt:

• True Strike + Fire Bolt: 0.45 * 22 = 9.9 DPR
• Flaming Sphere + Fire Bolt twice: 0.05 * 7 + 0.95 * 3.5 + 0.2025 * 22 * 2 = 12.585 DPR

So even if the target only fails its save against Flaming Sphere on a 1, not breaking concentration is better by a wide margine.

Special cases

Arcane Tricksters

Just take Find Familiar as one of your spells, and move it next to the target to get Sneak Attack.
Take Green-Flame Blade as a cantrip instead of True Strike, and use it to increase DPR all the time, not just when you do not have Advantage.

Eldritch Knight

From level 7, you can make an attack as a bonus action after casting a cantrip. So during 2 rounds you can do 4 attacks with disadvantage, or 1 with disadvantage on your first turn, then one with and one without on the second. If we only consider True Strike or the absence of it, than if your base hit chance is less than 50%, and have disadvantage, it makes sense to use it.
The best solution again is to pick a cantrip that does not need attack rolls, und just use that when you have disadvantage.

Sorcerer

The Quicken metamagic can be added to True Strike, so it is usable once per turn. Still, there are no great spells to use it for³, and you can do many more powerful things with your concentration.

Conclusion

You can manufacture situations where True Strike still wins against other cantrips, but they will be rare and unnatural.
You just have to have:

• disadvantage
• horrible base hit chance
• no other useful spell to cast
• not concentrating on more useful spells
• not beaten out of concentration
• definite knowledge the target will be alive and in range even next round

One exception

It takes a special kind of DM, and a special kind of party.
In case some of your party members always try to talk to the enemy before combat inevitably happens, you can prepare by casting True Strike round after round.
Most DMs would shoot it down, however, and start combat as soon as someone casts a spell that only has use in battles.

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1. at the time of the questions, there were much fewer cantrips available
2. if one of your allies is standing next to the target, two attacks are better than Advantage on one, even if you have Sneak Attack
3. Plane Shift also allows a save, most creatures that are worth a 7th level slot either have high save values, Magic Resistance, Legendary Resistance, or more of these at the same time
4. True Strike does not have range:Self, you must pick target on the first round, and if the situation changes, and you want to attack someone else, you lost the Advantage and the action
5. most concentration spells offer better things than damage, but those are hard to quantify

Answer 4

If you're a warlock, then you really, really want your Witch Bolt to hit, because if it misses, you haven't just expended an action, you've also uselessly expended up to 1/2 of your day's non-cantrip spellcasting.

If you only have one Arrow of Dragon Slaying.

How many of your combats are ambushes? If you are not ambushing, on favorable terrain, starting Invisible or Hasted, etc., then you're doing it the hard way.

Answer 5

If you are an Eldritch Knight you can use the following feature to cast True Strike before striking each round. As True Strike does not affect a strike until the next round, you would have to cast it "in advance" each round to effect the first strike in the next:

War Magic Beginning at 7th level, when you use your action to cast a cantrip, you can make one weapon attack as a bonus action.

You could do this to cancel disadvantage against a target that is difficult to hit, so cancelling disadvantage for a single normal strike is better than two strikes at disadvantage. I haven't done the maths but it looks like there will be a point at which this makes sense.

Alternatively the Eldritch Knight might really want to hit with the next single attack due to a limited duration effect on your weapon from the previous round.

The Eldritch Knight may be multiclassed with rogue and this would allow them to use their sneak attack on the single strike each round even in normal face to face combat.

A sorcerer could use metamagic (Quickened spell) to bring the casting time down to a bonus action and use it in the action in the same round, a targeted spell they really want to hit right now for instance. I can also see this as being useful for a multiclass sorcerer/rogue to gain advantage on their attack and thus use sneak attack in circumstances otherwise impossible, as above.

Answer 6

Here's a few possible scenarios where True Strike might make sense:

• You are playing a Rogue and have no other source of Sneak Attack. Advantage gives Sneak Attack damage, so one attack with Advantage gives better damage-per-round than two attacks without - and doubling the chance of a critical hit is fun when you also double sneak-attack dice (or Smite damage for a paladin).

• You have access to Quicken Spell metamagic (via either the Metamagic Adept feat or 3 levels in Sorcerer). Quickening the spell reduces the opportunity-cost to a bonus action - which means you still get a full action's worth of attacks while setting up for next round. Not bad on a gish build.

• Setting up for an attack-roll with a costly resource. Taking an extra round to set up Advantage is worth drastically reducing the odds your only 7th-level spell slot, or your last Arrow of Slaying, is wasted on a missed attack roll.

Answer 7

An extremely narrow niche case created with the Tasha's revamp of Bladesingers

A sixth level Bladesinger gets a special version of Extra Attack that lets them replace one of the attacks with a cantrip. If they are multiclassed to Rogue, of any archetype, then they only get one sneak attack per turn, so the second attack (assuming the first one hits and deals the sneak attack dice) is less valuable. In that circumstance, and assuming they can't get advantage any other way (and there are so many ways to get it for a caster Rogue), attacking once with sneak attack, then True Striking to grant sneak attack for the next round is worth something.

Thing is, it's not worth much, because by doing it, that sneak attack you perform can't be one of the Bladesinger melee cantrips compatible with sneak attack (Booming Blade or Greenflame Blade). And by the time you can pull off this combo (level 6 Bladesinger/Rogue 1 minimum), you're getting automatic bonus damage from the cantrips (damage that initially beats your pitiful number of sneak attack dice left over, thanks to going deep in Wizard). Even by level 20 (6 Bladersinger/14 Rogue), the sneak attack is worth 7d6, while Booming Blade is worth 3d8 (with a 4d8 kicker if the target moves); assuming the target does not move, your choice (in a steady state where they do this every round) boils down to:

1. Attack twice each round without sneak attack (assuming rapier and Dex +5), one of them with Booming Blade: One chance for 1d8 + 5 + 3d8 damage (23 avg), one for 1d8 + 5 (9.5 avg)
2. Attack once with sneak attack (replacing other attack with True Strike): Single attack with advantage for 1d8 + 5 + 7d6 (34 avg)

Assuming you have a 65% chance to hit without advantage (the system is designed around that), then that's worth 23*0.65 + 9.5*0.65 == 21.125 expected damage with Booming Blade plus regular attack, and 34*0.8775 == 29.835 expected damage with sneak attack + True Strike. That higher damage should be slightly discounted (in that it takes place later in the combat, so the lower earlier damage might be worth more, and it limits you attacking one target, who might be dead or unavailable next round), but it's meaningfully higher.

Of course, to get that much of a benefit, you're looking at the level 20 build of the character; the relative benefits decrease at lower levels (Booming Blade's 1d8 is higher than the 1d6 sneak attack until you're at least Bladesinger 6/Rogue 3, and being potentially able to deal your Dex mod twice, not just once, is worth at least another die or two of sneak attack damage), few games occur at that high a level, and by level 20, you should have figured out some better way to get advantage reliably (e.g. a 13th level Arcane Trickster can give themselves advantage by distracting with Mage Hand as a bonus action, with none of the limits of True Strike; any rogue can just choose to not move and use Steady Aim to sneak attack at range, etc.), so in practice, I agree with András's answer: It's a useless cantrip in basically all circumstances, especially when compared to "having any other useful cantrip" instead.