Polymorph Fatigue (5e Variant Rule)
From D&D Wiki
Some players may like the polymorph spell a little too much… To add some more fluff to these types of spells, you now may get negative effects if you polymorph too often. You can also add this as a curse to any magical item like Dragon Mask, turning you into a (random) creature.
How it works
Every time you cast Polymorph, True Polymorph or Shapechange, you make a DC 15 Wisdom or Intelligence saving throw (chose one). If you fail the saving throw, your body has polymorph fatigue for 1d10+2 days. Every time you change shape with Shapechange you need to redo the saving throw.
Having polymorph fatigue doesn’t affect your normal abilities, but it makes you weaker to possible side-effects of polymorphing into another creature.
Whenever you try to polymorph into a creature other than your true form while under effect of polymorph fatigue, you need to make Wisdom or Intelligence saving throw (choose one ability for all your throws) against a DC of 10 + CR of the creature (rounded up) you transform in.
Special Saving Throws
Every saving throw has a special effect. You may choose which saving throws you do and in what order. You may decide to fail a saving throw, although I don’t know why you would want to do that…
- Amnesia: When you fail this saving throw, you forget that you were once another creature. This effect ends when the spell ends. However, you won’t remember what happened when you were polymorphed.
- Mind influence: When you fail this saving throw, your alignment changes into that of the creature you turn into. Your DM may decide that the PC becomes under his control when their alignment changes.
- Physical change: When you succeed this saving throw, you may replace the lowest ability scores by its higher counterpart. However, if you fail, you replace the higher ability score with its lower counterpart.
- Sex Swap: If applicable you turn into the sex opposite to your current sex when you fail this saving throw.
For Shapechange Only:
- Class change: When you fail this saving throw, you (or your DM) may pick a new class having a connection with your creature type. The level of this class is equal to the CR of this creature, unless stated otherwise. If you turn into a Drow Mage for example, your class would turn into a 10th level wizard, as that’s the level of its spellcasting triat.
- Broken shapechange: When you fail this saving throw, you can’t shapechange into any other creature during the effect of the spell.
You keep doing saving throws until you succeed one or failed three saving throws. If you failed three saving throws, you lose control over your body as the mind of the creature takes over. For the duration of the spell, your character gets controlled by the DM.
Variant on the variant rule
Every time you polymorph, you need to make these saving throws. Use this variant only if you want to discourage players into polymorphing.
As a Curse
When people acquire Polymorph Fatigue without interacting with any polymorph spell, it’s a curse. Most people call this the “Curse of Polymorphing”. You may acquire this curse from a cursed magical item, like a collar, bracelat, amulet or even a full-blown suit. But also from a goo-like substance or certain oozes.
Transforming due to this curse can take some time. Growing claws or scales only take 1 round, but everything that changes the anatomy (like growing a snake head or tail) will take 1 minute. If you grow or shrink atleast one size, the transformation will take 10 minutes. During this transformation, the victim may experience great suffering when there bones are violently reconfigured. You also can't level while polymorphed (unless your DM is VERY kind).
The curse works in almost the same way as the normal fatigue, but it is definitive. You can still choose which saving throws you want to do from the saving throws section and you can choose between both the Polymorph and Shapechange ones. If the creature they're turning into is of a higher CR than the PC, they automatically fail all three saving throws (and the DM may decide which ones...).
Curing this curse, however, is not simple. If you got transformed by a goo-like substance or ooze, you can cure it with a greater restoration spell, but transformations due to cursed items are a real hasle. It’s not widely known that they auto-attune to any creature wearing the item. So, to cure it, you’ll first need to cast a remove curse to end the attunement to the item. Only after you’ve done that, you can cast greater restoration on the affected player. However, if they forget to remove the item, the transformation will restart after 1 minute with the item auto-attuning to the creature again.
If you decide to wear the same cursed item a second time, you don’t reroll the saving throws, but use the same ones as the first time you came in contact with the curse.