Basilissa Aynia, the Dark Host

Flying, vigilance
{x}{x}, {t}: Each other creature gets -X/-X until
end of turn and you lose X life. Activate this
ability only any time you could activate a sorcery.
As long as you have less than half your starting
life total, Basilissa Aynia, the Dark Host gets
+4/+4 and gains "Whenever this creature attacks,
each opponent loses 2 life."