Is Restless Reef legal in Standard, Modern, and Commander?

Restless Reef is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Restless Reef

Q: What type of card is Restless Reef?

Restless Reef is a Land. Its oracle text reads: "This land enters tapped. {T}: Add {U} or {B}. {2}{U}{B}: Until end of turn, this land becomes a 4/4 blue and black Shark creature with deathtouch. It's still a land. Whenever this land attacks, target player mills four cards."