When you use Mismagius’s Cursed Prose attack, it applies an effect to the target Pokémon that causes it to take 90 damage at the end of your opponent’s next turn. However, all effects applied to a Pokémon are removed when that Pokémon retreats to the Bench. Because of this, if the Defending Pokémon hit by Cursed Prose retreats before the end of your opponent’s next turn, the attack’s effect will be removed and the Pokémon will not take damage.
Example: You use Mismagius’s Cursed Prose attack on your opponent’s Active Pokémon.
1. During your opponent’s next turn, they retreat their Active Pokémon hit by Cursed Prose to the Bench (such as by discarding Energy equal to the Pokémon’s Retreat Cost).
2. Because your opponent’s Active Pokémon retreated to the Bench, the effect of Cursed Prose is removed from it and it will no longer take damage at the end of your opponent’s turn.