Siastel, Forgotten King

Deathtouch, haste, vigilance, flying, indestructible, double-strike, shroud
Siastel, Forgotten King must attack each turn
if able, and must be blocked if able.
Whenever a creature becomes tapped or
untapped, Destroy target permanent.
{p/b}{p/b}{p/b}{p/b}: Untap each creature you control.
{6}{c}{c}{b}{b}{p/b}{p/b}: each opponent loses the game.