Boon of the Swamp (5e Epic Boon)
From D&D Wiki
Boon of the Swamp
Description: By some unnatural force by a God of Nature or something else you are transformed into something more.
You grow scales that increase your natural armor by 2 and resemble that of a crocodile
You gain the ability to breath underwater
Your teeth fall out and are replaced by sharper ones giving you a strength bite attack of 2d4 if you already have a bite attack then it is increased by 1d6
Your body starts producing less natural heat making you vulnerable to frost damage and require ways to keep warm in colder environments