Stoppered Time

At the beginning of your upkeep, choose one you have not already chosen:
-Pay {u}{u}{g}{g}, put a charge counter on this.
-Lose 5 life, put a charge counter on this.
-Exile a creature you control, put a charge counter on this.
-Sacrifice this.
{t}, Sacrifice Stoppered Time. If it had 3 charge counters on it, add 15 mana of any colour to your mana pool.