Is King Crab legal in Standard, Modern, and Commander?

King Crab is legal in: Legacy, Vintage, Commander.

King Crab

Q: What type of card is King Crab?

King Crab is a Creature — Crab. Its oracle text reads: "{1}{U}, {T}: Put target green creature on top of its owner's library. *"I'm allergic to shellfish—not only did it kill my entire village, it also gave me this nasty rash." —Olivia, fisher* Power/Toughness: 4/5"