Is Archipelagore legal in Standard, Modern, and Commander?

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

Archipelagore

Q: What type of card is Archipelagore?

Archipelagore is a Creature — Leviathan. Its oracle text reads: "Mutate {5}{U} (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, tap up to X target creatures, where X is the number of times this creature has mutated. Those creatures don't untap during their controller's next untap step."

Creature — Leviathan

$0.24 ↗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.)

Whenever this creature mutates, tap up to X target creatures, where X is the number of times this creature has mutated. Those creatures don't untap during their controller's next untap step.

Set Ikoria: Lair of Behemoths

Rarity Uncommon

Mana Value 7

Artist Svetlin Velinov

Collector # 41