Activated abilities of creatures that include a tap symbol in its cost require continuous control over the creature since the beginning of the players most recent turn: 602.5a
Despite this, however, a number of incredibly powerful Role Token cards have already been revealed
Some of Magics most busted cards rely on the graveyard, so building around self-mill gets you off to a strong start, especially in Commander, where games go long
If Kraum was the first spell you cast this turn, the next spell you cast this turn is your second spell
Avatar of Fury, Ghalta, Primal Hunger, Bedlam Reveler, and Thought Monitor are just a few of the expensive at first glance creatures that Ive played over the years, and they dont even begin to scratch the surface of playable cards that offer steep discounts when casting them