Curse of Ill Entry (5e Curse)
From D&D Wiki
Curse of Ill Entry
Whenever a creature affected by this curse willingly passes through a door, closed archway, portal, or any other artificial boundary marking a transition between two distinct spaces, they take 1 necrotic damage. This damage cannot be reduced or prevented in any way.
The curse can be broken by casting remove curse with a spell slot of 5th level or higher.