Is Cephalid Illusionist legal in Standard, Modern, and Commander?

Cephalid Illusionist is legal in: Legacy, Vintage, Commander.

What type of card is Cephalid Illusionist?

Cephalid Illusionist is a Creature — Octopus Wizard. Its oracle text reads: "Whenever this creature becomes the target of a spell or ability, mill three cards. {2}{U}, {T}: Prevent all combat damage that would be dealt to and dealt by target creature you control this turn. Power/Toughness: 1/1"