Time Stone

If Time Stone would become untapped while it has a burden counter, instead remove a burden counter from it.
{t}, {1}, {u}: Time Travel.
{t}, {2}, {u}, put a burden counter on Time Stone: return target permanent card in a graveyard that was put there from the battlefield this turn to the battlefield under its owner's control.
{t}, {x}, {x}, {x}, {1}, {u}, put four times X burden counters on Time Stone: Take X extra turns after this one. Activate only during your turn.