Is Huntmaster Liger legal in Standard, Modern, and Commander?

Huntmaster Liger is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Huntmaster Liger

Q: What type of card is Huntmaster Liger?

Huntmaster Liger is a Creature — Cat. Its oracle text reads: "Mutate {2}{W} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.) Whenever this creature mutates, other creatures you control get +X/+X until end of turn, where X is the number of times this creature has mutated. Power/Toughness: 3/4"

Creature — Cat

Mutate (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.)