Is Agatha of the Vile Cauldron legal in Standard, Modern, and Commander?

Agatha of the Vile Cauldron is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is Agatha of the Vile Cauldron?

Agatha of the Vile Cauldron is a Legendary Creature — Human Warlock. Its oracle text reads: "Activated abilities of creatures you control cost {X} less to activate, where X is Agatha's power. This effect can't reduce the mana in that cost to less than one mana. {4}{R}{G}: Other creatures you control get +1/+1 and gain trample and haste until end of turn."

Agatha of the Vile Cauldron

Legendary Creature — Human Warlock

Activated abilities of creatures you control cost less to activate, where X is Agatha's power. This effect can't reduce the mana in that cost to less than one mana.