Does a Dark Arts Potion resolve on every player's turn, or only on its holder's turns?

Question

Accepted Answer

Only on its holder's turns. A Dark Arts Potion stays face up in front of the hero who drew it and resolves at the start of that hero's turns until it is brewed. Its scope depends on the card text: some affect all heroes, some you and your neighbours, and some only the active hero.

Harry Potter: Hogwarts Battle

Does a Dark Arts Potion resolve on every player's turn, or only on its holder's turns?