A demonic entity takes up residence within your body. The demon is jealously possessiveāit becomes your Cohort and you can't gain a new one. Unlike other Cohorts, the demon isn't a separate entity and doesn't take its own turn. Instead, you transform into the demon using the following rules.
Shape-Shift
You can use a Bonus Action to shape-shift into the demon or return to your normal form. While shape-shifted, your game statistics are replaced by the Demon Cohort's stat block, but you retain your Hit Points, Hit Point Dice, Intelligence, Wisdom, and Charisma scores, class features, and feats. You choose whether your equipment merges into the demon or is worn by it.
Temporary Hit Points
When you are shape-shifted into the demon, you have Temporary Hit Points equal to the demon's Hit Points, which last until you return to your normal form. When you lose Temporary Hit Points, the demon loses an equal number of Hit Points. If you no longer have Temporary Hit Points or the demon is reduced to 0 Hit Points, you return to your normal form and can't shape-shift into the demon until the demon regains any Hit Points.
Demon in Combat
Unlike other Cohorts, the demon doesn't take a separate turn in combat.
Restoring the Demon
The demon gains the benefits of taking a Short or Long Rest as normal. Spells and other effects that restore Hit Points can target you or the demon while you are shape-shifted. When the demon regains Hit Points, the number of Temporary Hit Points it grants you increases by an equal number. If the demon is reduced to 0 Hit Points, it regains 1 Hit Point after 1 minute, allowing you to shape-shift into it again.