Ungoliant, All-Consuming

At the beginning of your upkeep, and whenever
a player casts a spell, sacrifice a creature. If you
can't, sacrifice Ungoliant, All-Consuming.
When Ungoliant enters the battlefield, each
player loses a third of their life, rounded down.
{b}{b}{b}{b}, {t}: Ungoliant can't be targeted by
spells or abilities until end of turn.