Metamorphosis [Arabian Nights] Snow Creature if they were attacked this

if they were attacked this turn by an Assassin you controlled

WHEN SPINOSAURUS ENTERS THE BATTLEFIELD

It's like that

Set: Ravnica Allegiance Guild Kit Type: Creature — Thrull Rarity: Rare Cost: {4}{W}{B} Extort (Whenever you cast a spell

Set: The Lord of the Rings: Tales of Middle-Earth Tokens Type: Token Creature — Orc Army Rarity: Common Food

Metamorphosis [Arabian Nights] Snow Creature if they were attacked thisSet: Arabian Nights Type: Sorcery Rarity: Common Cost: {G} As an additional cost to cast this spell, sacrifice a creature. Add X mana of any one color, where X is 1 plus the sacrificed creature's mana value. Spend this mana only to cast creature spells.