Alastor, The Radio Demon

{x}: Sacrifice a creature, deal X damage to any
target, where X is the sacrificed creature's
converted mana cost.
{x}{u/b}{u/r}{b/r}: Alastor, The Radio Demon
and target creature become "Contracted",
where the target creature gets -X/-X and
Alastor, The Radio Demon gets +X/+X,
until end of turn or until target creature leaves
the battlefield.