Commander's Monument

{t}: Add {c}{c}. If this mana is spent to cast a spell
from your command zone, you gain an amount
of life equal to its mana value.
{x}: X is the mana value of your commander plus
an additional {2} for each time you've cast your commander this game. Commander's Monument becomes a copy of your commander, except it
isn't legendary. Exile it at the beginning of the
next end step.