Tengu format ruling
Chthonian Polymer
Card effect (current official text)Activate only when your opponent Fusion Summons a Fusion Monster. Tribute 1 monster to take control of that Fusion Monster.
Rulings
- Tributing 1 monster is a cost to activate "Chthonian Polymer".
- You can only activate this card when the opponent Fusion Summons a monster, including with a Special Summon that is treated as a Fusion Summon, like "Miracle Fusion" or "Power Bond". You cannot activate it when they Special Summon a Fusion Monster with a card effect, like "Metamorphosis" or "Cyber-Stein".
- You gain control of the Fusion Monster for as long as it remains on the field.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.