Is Vadrok, Apex of Thunder legal in Standard, Modern, and Commander?

Vadrok, Apex of Thunder is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Vadrok, Apex of Thunder

Q: What type of card is Vadrok, Apex of Thunder?

Vadrok, Apex of Thunder is a Legendary Creature — Elemental Dinosaur Cat. Its oracle text reads: "Mutate {1}{W/U}{R}{R} (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.) Flying, first strike Whenever this creature mutates, you may cast target noncreature card with mana value 3 or less from your graveyard without paying its mana cost."

Legendary Creature — Elemental Dinosaur Cat

$0.89 ↗20 similarCommander, Modern

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.)