Clock Tower Reversal

When Clock Tower Reversal enters the
battlefield, (Choose) you gain 1 life for each
creature in your graveyard or on the field.
{t} Add {g}{g}{g} to your mana pool.
{x}{g}, Target creature gets {x} +2+1
counters on it.
{6}{g}, All creatures on your side of the field
get +4+4, gain trample and vigilance.