Million-Century Ice Prison (MP24-EN377) - 25th Anniversary Tin: Dueling Mirrors 1st Edition

During the Main Phase, if a monster(s) you control leaves the field by an opponent's monster effect, except by being destroyed: Activate 1 of these effects;
• End the Main Phase.
• Skip Main Phase 1 of your opponent's next turn.
You can only activate 1 "Million-Century Ice Prison" per turn.