Beneath the Waves

This enters tapped unless you control 3 basic lands
{t} Add {u} or {b}
{t}{u/b}{u/b}{u/b}{u/b} Sacrifice Beneath the waves; Activate this only if you control 2 other lands called beneath the waves put a 20/20 Black legendary avatar creature token in play with flying and indestructible called Marit Lage into play