Ulgathoth the Shadow

Unblockable, Infect, Shroud
If Ulgathoths toughness is 0 or lower it is not destroyed.
If Ulgathoths toughness is above 0, exile it.
{b}{b}: Ulgathoth gets +1/+0.
{b}{b}{b}{b}{b}: Ulgathoth fights target creature, only activate this ability whenever
you could cast a sorcery.