Gashad, Ever-Growing

Skeletons you control have deathtouch.
Whenever you regenerate Gashad, Ever-Growing,
you may exile a skeleton card from the battlefield
under your control or your graveyard. Gashad,
Ever-Growing gets +X/+X where X is equal to
the total power of cards exiled with this ability.
{1}{b}{g}: Regenerate Gashad, Ever-Growing