Sacred Cavern of Life

{t}: Add {1} to your mana pool.
Whenever you tap Sacred Cavern of Life for mana, you gain life equal to the number of lands you control.
{t}, Sacrifice Sacred Cavern of Life: Exile it and put it back onto the battlefield under your control on the beginning of your next upkeep. Your life total is doubled until the end of turn.
The energy of life is sacred, and it cannot be destroyed. But if you manage to break its secret, it might gift you on some way.