Oketra, Avenger of Amonkhet

Double strike, first strike, indestructible
Oketra, Avenger of Amonkhet can't attack unless your opponent is playing a red, black, or blue deck.
{w}{4}: Destroy target nonland, noncreature permanent. Lands you control gain "If you would tap this land, add {w} to your mana pool" until end of turn.