I'm D.M.'ing a 5th edition D&D game, My friend recently came to me begging for me to include fusion (in the vein of Dragon Ball Z) into my campaign. Personally, I have no hang ups introducing this mechanic into my game, however I am at a loss as to how to actually pull it off.

The Idea would be that two Player Characters would fuse into one, stronger character, both of their skills and abilities should be represented in the transformation.

I feel as though just adding the 2 separate EXP levels together would give them too much of an advantage.

so ultimately my question becomes; Does anybody know of any rules or have any ideas that are relevant to character fusion in 5th edition D&D?

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    \$\begingroup\$ "Homebrew this for me" questions are generally closed: rpg.meta.stackexchange.com/questions/5782/… \$\endgroup\$ – Icyfire Oct 6 '17 at 17:11
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    \$\begingroup\$ Please refrain from posting answers in comments. Use comments only to suggest improvements or request clarification. \$\endgroup\$ – doppelgreener Oct 6 '17 at 18:01
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    \$\begingroup\$ Also do not post answers that are untested homebrew or brainstorms. These will be downvoted and/or deleted as they do not meet site quality guidelines. \$\endgroup\$ – mxyzplk - SE stop being evil Oct 6 '17 at 19:35
  • \$\begingroup\$ If this question were simply edited to ask for rules for fusion and not "ideas" it'd be reopened; we'd delete all extant answers as speculation possibly excepting the one mentioning the applicable 3.5e mechanic but then it could get new, real answers... \$\endgroup\$ – mxyzplk - SE stop being evil Oct 8 '17 at 0:40

A simple way to do this was to take the characters and join them as if you were multi-classing a single character. For example, let's say you had a lvl5 Trickster Rogue and a lvl5 Hunter Ranger.

  • Pick one of the characters (on randomize it, or alternate it, or...) to be the base character, who absorbs the other.
  • Assuming your picked the Rogue, start adding Ranger levels to that character using the same choices as the original Ranger did (Hunter specialization, spells (when applicable), etc)
  • Remove HP (based on missing HP from original characers), spell slots, and add current conditions (poison, blind, fatigue,...) to the new character

In the end, you have a lvl10 character with 5 Rogue levels and 5 Ranger levels, and a pretty decent fusion of your players characters. This character (with both versions of the base character) should be created outside the game, so as to not delay the game a lot.

That being said, I find this homebrew to be a cool idea to do once, and that's about it. You will have 2 players wanting to control this character :

  • They may disagree on what to do, how will they solve this problem? Roll against each other?
  • Combat might be even more boring (they essentially will play every other turn in combat)

You will also have imbalanced characters, a lvl10 monster in the middle of a lvl5 party will outshine everyone else. Your other players might not enjoy this. It also means you have to tailor encounters for this specific character, and you'll essentially be creating bosses that the party could not defeat otherwise.

Erik: Actually, I think this merger won't make the combined character all that powerful; you don't have higher level spells than normally, your proficiency is probably only 1 point higher, your AC stays the same, but you lose half your actions.

AndrĂ¡s: Losing half your actions will make this character actually weaker than the 2 halfs alone. The biggest advantage is taking "half" damage from area spells compared to 2 characters.

Finally, multi-classing only works up to lvl20, so with higher-level characters, you'll need to homebrew even more stuff.

PS: This could be an interesting thought if you had a player join in the middle of the campaign wanting to play 2 separate characters, but with the option of joining them at will. So a party of lvl10 characters, and he would be playing two lvl5 characters, leveling one of them at a time. Maybe it could work, I've never done such a thing.

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    \$\begingroup\$ Actually, I think this merger won't make the combined that character all that powerful; you don't have higher level spells than normally, your proficiency is probably only 1 point higher, your AC stays the same, but you lose half your actions. (Exception is if both characters have the same class, in which case this answer wouldn't work.) \$\endgroup\$ – Erik Oct 6 '17 at 8:53
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    \$\begingroup\$ Losing half your actions will make this character actually weaker than the 2 halfs alone. The biggest advantage is taking "half" damage from area spells compared to 2 characters. \$\endgroup\$ – András Oct 6 '17 at 9:02
  • \$\begingroup\$ Okay, maybe the character would be as broken as I thought he would. I've added your comments to the answer, I think they are quite adequate. \$\endgroup\$ – BlueMoon93 Oct 6 '17 at 9:56
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    \$\begingroup\$ Have you seen this idea used in practice? \$\endgroup\$ – Wibbs Oct 6 '17 at 10:46
  • \$\begingroup\$ @wibbs Nope. It has never even been mentioned at our table \$\endgroup\$ – BlueMoon93 Oct 6 '17 at 19:18

So 3.5 actually had a psionic power called Fusion that does pretty much exactly what you're asking for. A summary of how it works is:

  • The person who initiates the fusion is in control of the fused character.

  • The fusion has the total current hit points of both contributing characters.

  • All class features and abilities are available/applied to the fusion; when both characters had the same feature, they don't stack.

  • The fusion has the better of the two characters' attack rolls, saves, and ability scores.

  • The initiator picks which equipment the two characters had that the fusion has access to. Everything else gets absorbed.

  • when the fusion ends, damage taken or healed is split among the characters.

This doesn't use any stats intrinsic to 3.5 (beyond the ability itself), so it should be straightforward to use it in 5e.

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  • \$\begingroup\$ I believe a previous question addressed whether you could use this power to fuse multiple characters, though I'm afraid I don't have the link handy. \$\endgroup\$ – TheVagrantDog Oct 6 '17 at 16:21

This answer is mainly for 3rd edition, 3.5 or Pathfinder, rather than for 5th edition, though it may provide some useful ideas.

In 3rd edition D&D and its variants, power levels are exponential, so a 10th level character isn't just 2x as powerful as a 5th level character, they're much more powerful (I think 5th edition reduced this curve a little). Typically fights are decided by the action economy: a group of five adventurers can take down a single powerful opponent because they get to do five times as many things per round. The whole point of a fused character is to be powerful enough to outweigh that loss of actions, but you need to keep the power increase from being ridiculous.

So to achieve this result in 3rd, I'd suggest that instead of adding any numbers together, you should take the upper of the two.


  • For each ability, use the higher of the two scores and modifiers. However this modifier is rarely used - see below.
  • Use the adjusted DEX modifier for calculating Armor Class, but force them to a choose a single set of armour and equipment. Bonuses to Armour Class combine, but do not stack; so if both characters have the Dodge feat, the fused character only has that benefit once.
  • If they have damage reduction, use whichever number is higher but make it overcome by either set of weaknesses; so if one character has DR 5/magic and another has DR 10/adamantine, the fused character would have DR 10/(magic or adamantine).

Attacks and abilities

  • Take whichever base attack bonus is higher, and the adjusted STR modifier, and use that to calculate attacks.
  • For each saving throw, take whichever TOTAL bonus is higher (ignoring the ability modifier and other components of it). Allow the use of conditional bonuses from either character.
  • Allow them to use the full class abilities of either character - spells, skills, sneak attack, etc - but not in the same turn. So they cannot combine Power Attack from one character with Sneak Attack from another.
  • Force them to choose a single weapon when fusing.


  • If both characters have spells, the fused character can use any spell known by either of them.
  • Track them separately. So, for example, Cleric spells are taken from the Cleric's pool while Ranger spells come from the Ranger's pool.
  • Spell save DCs, however, should be the higher of the two for that level.
  • The caster level for spells is still their base level, or the higher of their base levels if different.


  • The fused character can use any skill known by either character.
  • For each skill they have, use the highest TOTAL bonus.

Hit points

  • Use whichever max hit point is higher.
  • Track hit points separately from either character.
  • When the fused character's hit points reach zero or lower, forcibly split the characters and divide the damage equally between them. The characters are then stunned for their next round.
  • Temporary effects end when the fusion ends. This applies both to positive effects like Haste, and negative effects like Doom.

The above has the advantage of minimal calculation. They could even run it on the fly, with both character sheets in front of them, without pre-calculating anything.

How you divide control between the two characters is a question for your GM style. Ideally the players should agree in advance.

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  • \$\begingroup\$ minor nitpick, you say power levels are logarithmic, but I think you mean exponential. 5E is logarithmic in style. \$\endgroup\$ – Tal Oct 6 '17 at 13:56
  • \$\begingroup\$ I've adjusted that word. To be fair, I think the maths is a bit more complicated than it merely being "exponential", but I don't know it. \$\endgroup\$ – Marcus Downing Oct 6 '17 at 14:00
  • \$\begingroup\$ Oh, and this answer comes with a big caveat: I haven't play tested it! It may need some fine-tuning with real play experience. \$\endgroup\$ – Marcus Downing Oct 6 '17 at 14:01
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    \$\begingroup\$ -1 because this answer is pure untested speculation \$\endgroup\$ – Icyfire Oct 6 '17 at 15:56
  • \$\begingroup\$ This solution would give the fused character (1) the best aspects of each of the source characters: the better of two saves, attacks, skills etc; (2) all the options from either character, including both pools of daily spells and other points. It doesn't give exceptionally high numbers to any one ability, but it makes the fused character implausibly perfect. \$\endgroup\$ – Marcus Downing Oct 6 '17 at 16:10

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