Is Summon: Leviathan legal in Standard, Modern, and Commander?

Summon: Leviathan is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Summon: Leviathan

Q: What type of card is Summon: Leviathan?

Summon: Leviathan is an Enchantment Creature — Saga Leviathan. Its oracle text reads: "(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Return each creature that isn't a Kraken, Leviathan, Merfolk, Octopus, or Serpent to its owner's hand. II, III — Until end of turn, whenever a Kraken, Leviathan, Merfolk, Octopus, or Serpent attacks, draw a card. Ward {2}"