The question is born from:
Does taking the form of a Muse using Fey Form gain you the Sound Strike attack?.
Is 20d6 sonic damage every turn overpowered compared to other 5th- to 7th character-level abilities?
Specifically, this would be accomplished by turning into a muse using the fey form spell and obtaining the Sound Strike attack, which we can break down to 5 ranged touch attacks that deal 4d6 sonic damage each.
It's hard to assess because obviously, you can not know all the cheesy or min-maxed build out there. But as a point of comparison, let's look as an actual group I know of (i.e. mine).
At level 5 to 7, a +16 to touch attack is almost guaranteed to hit. We will just flatly ignore the chance of hitting for this purpose, and assume you will land all hit, except on a 1.
20d6 average to 70 damage per turn, so 66.5 damage per turn (if you factor the crit fail).
Now, let's compare that to an actual group.
My lv 14 magus dishes out 11d6+5 (~38.5) on average, and has a hit chance of around 60% on average AC. With three attacks per turn (one gained from Haste), this amounts to roughly (60% x 38.5) x 2 + (35% x 38.5) = 59.675 damage per turn.
I'm oversimplifying the maths by not facturing the crits, but this is just a ballpark estimation.
My magus can produce that half a dozen times a day, since he is spell limited.
The other big hitters are, from bottom to top: A ranger (~65 average), a swashbuckler (~75 average) and a crit samurai (~80 average)1. All are loaded with magical items and are fairly efficient at min-maxing (it's not unusual for them to one-shot the bosses as presented in the AP).
So you would hit harder than some 14th level characters with approximately 95% chances of hitting at level 5. Ranged. At will. This is higher and more reliable than our 14th level ranger.
I'm not saying that there isn't some cheese or extremely powerful builds that can accomplish that by 5th or 7th level. But from a balance point of view, it sounds broken and overpowered. You will crush most encounters, which isn't fun nor rewarding for you or your group. My advice: don't.
This estimation is based on experience. It would be incredibly hard to produce the average damage per turn a character is supposed to output at a level, so I had to approach the problem from a simpler angle. If anyone can compute more accurate numbers, I'd be interested to see them. No doubt there are people knowledgeable enough on SE to do that.
1: This numbers are from the top of my head and rough figures. I don't know their exact average damage output, so I rounded it.
When compared to other effective builds that are available this is not too strong. I can not stress this strongly enough, a caster of equal level would be able to own you and be more effective against most emenies.
Let's look at a partial build using the Fey Form spell.
15 point buy, human, level 5 Shifter (Feyform), 18 Dexterity & 16 Wisdom. B.A.B of +5.
Feats: Point Blank Shot, Precise Shot (No -4 if your target is engaged in melee), Undersized Mount (You can ride creatures of your size category), and Weapon Focus (+1 to Atk). This will give you a ranged touch attack of +10 (within 30 feet +11 with a +1 damage to each attack). Because the Muse is medium size you will not get a boost to Dexterity from the Fey Form spell.
Ranged 5 sound strikes +10 ranged touch (4d6 sonic)
Percentage that all attacks will hit touch AC for the +10 attack: \begin{array}{|l|r|r|r|r|r|r|r|} \hline \text{Hits} & \text{AC 14} & \text{AC 15} & \text{AC 16} & \text{AC 17} & \text{AC 18} & \text{AC 20} \\ \hline \text{1} & 85\% & 80\% & 75\% & 70\% & 65\% & 55\%\\ \hline \text{2} & 72\% & 64\% & 56\% & 49\% & 42\% & 30\% \\ \hline \text{3} & 61\% & 51\% & 42\% & 34\% & 27\% & 17\% \\ \hline \text{4} & 52\% & 41\% & 32\% & 24\% & 18\% & 9\%\\ \hline \text{5} & 44\% & 33\% & 24\% & 17\% & 12\% & 5\%\\ \hline \end{array}
The odds for the +11 attack are slightly better:
\begin{array}{|l|r|r|r|r|r|r|r|} \hline \text{Hits} & \text{AC 14} & \text{AC 15} & \text{AC 16} & \text{AC 17} & \text{AC 18} & \text{AC 20} \\ \hline \text{1} & 90\% & 85\% & 80\% & 75\% & 70\% & 60\%\\ \hline \text{2} & 81\% & 72\% & 64\% & 56\% & 49\% & 36\% \\ \hline \text{3} & 73\% & 61\% & 51\% & 42\% & 34\% & 22\% \\ \hline \text{4} & 66\% & 52\% & 41\% & 32\% & 24\% & 13\%\\ \hline \text{5} & 59\% & 44\% & 33\% & 24\% & 17\% & 8\%\\ \hline \end{array}
This list isn't exhaustive by any means. I mainly checked CR 5 enemies. I barely looked at other CR's and only added a bare minimum of their strengths, assumed to be ran by a semi competent GM! Look at each monster and the percentages to hit seen above to see that Fey Form Shifter is not overpowered! Average damage will be 17 sonic per hit, consider other factors by each enemy that will significantly change this! For a monster that doesn't have the Dodge feat, trade one of their feats for it. GM's have been encouraged to tweak monsters on many occasions.
CR5
AC 14
As you can see above, enemies with a good touch AC or better, is definitely a weak point for Fey Form (Muse) You will need to consider that it's a ranged natural attack. So each attack will provoke an attack of opportunity if you are threatened, you know some monsters actually have 10 ft. reach or more (gasp). If you move more than a 5-foot step you may only make a single attack (a mount will take care of this) Also in some situations your enemy may have cover (+4 to AC) due to terrain (e.g. closed in spaces) with allies possibly getting in the way. Spells such as a high DC Colorspray (Awesome Display), Mudball, or Stinking Cloud will own your @$$. Mirror Image is a common spell that would buy a character a round against Fey Form (Muse). If intelligent enemies learn about your tactic, Resist Energy, Communal (Sonic) on a enemy team could change the outcome of the battle.
Here is a build to compare it to (This will be a long post, so I'm just posting one comparison build with a particular regard to damage. I could have made this build more optimal, but purposely chose not so.).
15 point buy, human, level 5 Fighter (Dragoon), 18 Strength & 16 Dexterity. B.A.B of +5.
Feats: Mounted Combat, Ride by Attack, Spirited Charge, Power Attack, Furious Focus, Weapon Focus, and Weapon Specialization.
Item +1 lance.
Mount Dire Bat Combat trained.
Charge Attack +14 (+15 if flying above) (3d8+51)
Percentage that attack will hit AC of 19, 21
\begin{array}{|l|r|r|r|r|r|r|r|} \hline \text{Attack} & \text{AC 19} & \text{AC 21} \\ \hline \text{1st +10} & 80\% & 70\%\\ \hline \text{1st +15} & 85\% & 75\%\\ \hline \end{array}
Average damage 64.
Closed in spaces. Charging limitations and many of the spells listed above.
While Fey Form (Muse) is good, it's not overpowered. Well built casters generally have variety and power.
A Summoner spirited charge build will be more powerful than the Fighter build above. Mainly due to the eidolon and the spells.
Ultimately, a caster with top spell selections (mainly battlefield control/save or suck) could shut these guys down, and be more valuable in most situations.
*I'm assuming a competent GM. If he's running a Paizo adventure, then not running it as is. Their adventures are heavily skewed toward the PC's (e.g. weak enemies, poor combat advice for running monsters) and any effective 5th level build would be overpowered if such adventures are ran without changes.
You wouldn't be able to do it at all. Fey Form: "You can more easily cast spells that the creature has as spell-like abilities, although you must still cast them as normal for your class. When you cast a spell that the creature has as a spell-like ability, it requires no verbal or somatic components and can’t be countered." Muse: Ranged 5 sound strikes +16 ranged touch (4d6 sonic)
The 5 sound attacks count as a ranged attack, NOT as a spell the Muse knows. That feature of Fey Form only applies to spells, not every single thing that Fey can do. There is a list provided of spells the Muse knows. If your character even CAN cast those spells, then you can cast them as spell-like abilities instead, requiring no somatic or verbal components and also being un-counter-able. Which is nice but not NEARLY as OP as obliterating every encounter with 5 +16 TOUCH ATTACKS LOL.
