Jefftor, Skeletal BattleMage

{r}{1}: Jefftor gains +1/+1 for each instant or
sorcery in your graveyard until end of turn.
{u}: Jefftor phases until end of turn.
{b}{b}: return target creature with cmc less than
Jefftor's current toughness. Sacrifice this creature
at end of turn.
{r}{u}{b}{x}: You may cast or play a card from your graveyard whose cmc is less than the amount of
mana used to activate this ability.