Aldaan, Vyscerion Forefather

Cannot be countered.
{u}{u}{b}{b}: Sacrifice a creature you control, put
a Soul counter on target artifact you control.
{u}{u}{b}{b}{t}: Remove a Soul counter from an
artifact you control, Aldaan gains Hexproof and Indestructible until end of turn.
You may remove X soul counters from artifacts
you control to add X mana in any combination of {u} and {b}.
Use this mana only to cast creature spells.
"Souls are fiddly little things..."