Is Stream of Thought legal in Standard, Modern, and Commander?

Stream of Thought is legal in: Modern, Legacy, Vintage, Commander, Pauper.

What type of card is Stream of Thought?

Stream of Thought is a Sorcery. Its oracle text reads: "Target player mills four cards. You shuffle up to four cards from your graveyard into your library. Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)"