Is The Master of Keys legal in Standard, Modern, and Commander?

The Master of Keys is legal in: Legacy, Vintage, Commander.

The Master of Keys

Q: What type of card is The Master of Keys?

The Master of Keys is a Legendary Enchantment Creature — Horror. Its oracle text reads: "Flying When The Master of Keys enters, put X +1/+1 counters on it and mill twice X cards. Each enchantment card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.) Power/Toughness: 3/3"

Legendary Enchantment Creature — Horror

Flying

When The Master of Keys enters, put X +1/+1 counters on it and mill twice X cards.

Each enchantment card in your graveyard has escape. The escape cost is equal to the card's mana cost plus exile three other cards from your graveyard. (You may cast cards from your graveyard for their escape cost.)

Power/Toughness: 3/3

Set Duskmourn: House of Horror Commander

Rarity Mythic Rare

Mana Value 3

Artist Wisnu Tan

Collector # 4

Scryfall