Is my multiclassed paladin/fighter/sorcerer built according to the rules? [closed]

Question

I wanna preface this by saying I'm a D&D fanboy/wannabe, Baldur's Gate and Critical Role is the closest I've ever gotten to playing the game. One of the things I love about any game is character creation, I can sit in any game and just create a character for hours on end, so naturally I'd be interested in the D&D character creation process.

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Leveling

1. Paladin, you get Divine Sense and Lay on Hands
2. Paladin, you get Fighting Style (Great Weapon), Divine Smite, Cure Wounds and Detect Magic
3. Fighter, you get Fighting Style (Defense), Second Wind
4. Fighter, you get Action Surge
5. Fighter, you get Martial Archetype (Eldritch Knight), Mage Hand, Prestidigitation, Absorb Elements, Identify, Find Familiar (white raven)
6. Sorcerer, you get Sorcerous Origin (Divine Soul, affinity for law/good), Message, Thaumaturgy, Minor Illusion, Fire Bolt, Comprehend Languages, Ceremony, Bless (Divine Soul)
7. Sorcerer, you get Font of Magic, Feather Fall
8. Sorcerer, you get Metamagic (Quickened, Twinned), Detect Thoughts, replace Feather Fall with Alter Self
9. Sorcerer, you get Ability Score Improvement, Mending, Feather Fall
10. Sorcerer, you get Fireball, replace Feather Fall with Counterspell
11. Sorcerer, you get Origin Feature (Empowered Healing), Tongues
12. Sorcerer, you get Dimension Door
13. Sorcerer, you get Ability Score Improvement, Divination
14. Sorcerer, you get Teleportation Circle, replace Divination with Geas
15. Sorcerer, you get Metamagic (Empowered or Extended), True Strike, Mass Cure Wounds
16. Sorcerer, you get Disintegrate
17. Sorcerer, you get Ability Score Improvement
18. Sorcerer, you get Resurrection, replace Teleportation Circle with Teleport
19. Sorcerer, you get Origin Feature (Otherworldly Wings, eagle according to rules but I prefer white raven wings if allowed)
20. Sorcerer, you get Plane Shift

Final build at level 20

Hit points: (5d10(min 30) + 15d6(min 60)) + (Constitution mod * 20), at const mod +2 it's 130-180, at +4 it's 170-220

Hit dice: 5d10 + 15d6

Spells known: 28 (2 paladin rank 1, 2 wizard cantrips, 3 wizard rank 1, 6 sorcerer cantrips, 14 sorcerer, 1 sorcerer origin)

Spell slots: 4x1, 3x2, 3x3, 3x4, 2x5, 1x6, 1x7, 1x8, 1x9 (1 paladin, 1 fighter, 15 sorcerer = 17 multiclass level for spell slots)

Armor: Plate

Weapon: Greatsword

Spells/Abilities:

• Otherworldly Wings (Divine Soul, white raven wings)
• Lay on Hands (paladin)
• Divine Sense (paladin)
• Second Wind (fighter)
• Action Surge (fighter)
• Metamagic Quickened, Twinned, Empowered/Extended (sorcerer)
• Empowered healing (Divine Soul)
• Weapon Bond (Eldritch Knight)

0 : Mage Hand (wizard), Prestidigitation (wizard), Fire Bolt, Thaumaturgy, Minor Illusion, Message, Mending, True Strike

1 : Cure Wounds (paladin), Detect Magic (paladin), Absorb Elements (wizard), Identify (wizard), Find Familiar (wizard), Comprehends Languages, Ceremony, Bless (Divine Soul)

2 : Detect Thoughts, Alter Self

3 : Fireball, Counterspell, Tongues

4 : Dimension Door

5 : Geas, Mass Cure Wounds

6 : Disintegrate

7 : Resurrection, Teleport, Plane Shift

8 : -

9 : -

Fighting

For the normal fights you use mostly Fire Bolt that you spend sorcery points to empower. At level 11 as a sorcerer Fire Bolt deals 3d10 damage, using Quickened you can cast it twice on a single target, and optionally Twinned to cast on an additional target. For packs of creatures you use Fireball, but your main source of damage should be Fire Bolt as you save most of your magical strength for RP abilities and the boss fight combo.

In a boss fight the super combo is to have all 11 sorcery points at the start if you want to use Twinned, otherwise you just need 4, then use this combo on your turn:

• Action Surge
• Action 1: Disintegrate at 6th level on the boss
• Action 2: Disintegrate at 7th level on the boss, optionally Twinned against a second target
• Bonus Action 1: Disintegrate at 8th level on the boss using Quickened
• Bonus Action 2: Disintegrate at 9th level on the boss using Quickened

This should lead to being capable of dealing 10d6 + 40, 13d6 + 40, 16d6 + 40 and 19d6 + 40 damage to a single target in one turn, optionally with another 13d6 to a secondary target. That should kill most creatures you'll meet, if not then you still have double Fire Bolt spam and your basic fighting abilities to finish them off, or your allies can deal with what's left. You've done your part.

Notes

• You need at least 13 strength and 13 charisma in order to pick the paladin, fighter and sorcerer classes.
• I know some of this is not taken from the standard edition, like the Eldritch Knight archetype and Divine Soul origin.
• Originally it was supposed to be a demonic character with 9 figher and 11 sorcerer (pyromancer), but I had to make it 2 paladin 3 fighter 15 sorcerer in order to make the boss combo work, or else I wouldn't have the spell slots to cast 4 disintegrates. With more levels in sorcerer Divine Soul was more interesting than Pyromancer, and with the start as a paladin it just made sense to make the character a bit more good and holy, it makes it better for actual games as well since evil characters are generally unwelcome in most campaigns.
• Already when you first get Disintegrate at character level 16 you can use it twice on one target, at 18 you get thrice and then four times on a single target at level 20. The reasoning behind not picking other abilities at 6th rank and up (apart from more situational or rarely used spells like Teleport, Plane Shift and Resurrection) is that you want to save all those spell slots for the boss combo. Since your fighting is done either as fire bolt, fireball or disintegrate all other spells are focused around roleplaying and situational abilities.
• The build is centered around the two concepts of casting multiple Disintegrate spells and being an armored sorcerer with a two handed sword.
• I know that anything is possible with the power of the DM at your side, but I'd like this build to be usable for, if not all, then most campaigns.

Question

Is this character built according to the rules?

Answer 1

No, there are a number of errors

From the top:

Hit points

5d10 is not minimum 30 - its minimum 14. 15d6 is minimum 15.

At first level you get maximum hp - 10. At each subsequent level you choose to roll the dice and take what you get (which could be a 1) or take the mean + 0.5 (6 for a d10, 4 for a d6).

Spells Known

Paladin 2nd level - All first level paladin spells, you can prepare 1 plus your Charisma modifier.

Fighter (Eldritch Knight) 3rd level - 2 cantrips and 3 first level Wizard spells.

Sorcerer (15th level) - 6 cantrips and 14 Sorcerer spells. If you do not swap out spells they will be 3/1, 2/2, 2/3, 2/4, 2/5, 1/6, 1/7, 1/8 - (see Is there an easy way to validate a high-level Sorcerer's spell list?).

Spell Slots

Correct.

Prepared Spells

I'm not going through that in detail but you can only have 1 + Charisma bonus 1st level Paladin spells prepared (you can use any of them and change each day), 2 Wizard cantrips and 3 1st level Wizard spells which you cannot change, and 6 cantrips and 14 Sorcerer spells of whichever level is consistent with swapping out on level up which you cannot change.

I think you've done this correctly.

You have overlooked the additional spell you get from Divine Magic.

Fighting

Cantrip damage is based on total character level, not class level so your Firebolt does 4d10 damage at 20th level. Your metamagic options are OK but you only have 15 sorcery points per long rest (unless you change spell slots to points) - Quickened costs 2 and Twinned costs 1 so your proposed use of Firebolts is expensive.

Action Surge gives you an additional action - it does not give you another bonus action.

You can use your action and your Action Surge to cast 2 Disintegrates but you cannot use your bonus action as well. On p.202 of the Players Handbook it says that if you cast a spell with a casting time of 1 Bonus Action (which Quickened spell does) "You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action." Do not use Quickened spell when using your Action Surge - casting any bonus action spells limits you to one and only one 1 action cantrip no matter how many actions you have.

One small side issue - Disintegrate disintegrates. So, if the BBEG is carrying stuff that you would like to loot, you can't.

Notes

Eldritch Knight is in the Player's Handbook. Divine Soul is not, so it is subject to the approval of your DM. For Adventurer's League play, this is all OK but you are committed to Xanathar's and the Player's Handbook as your only sources.

Multiclassing is in the PHB, but is technically an optional rule and so it's also subject to DM approval.