Anne Frank's Attic

Exert (Exerted land won't untap during your
next untap step)
{t}, add {w}{w} to your mana pool
{t}, pay {w}{w}{w}{w} your creatures gain indestructible until end of turn
{t}, {w}{w}{w}{w}{w}{w} pay fifty life, if you live
after paying fifty life you win the game