"Though it may take an eternity, I will see the myriad dynasties united once more."

Anrakyr the Traveller

Lord of the Pyrrhian Legions — Whenever Anrakyr the Traveller attacks, you may cast an artifact spell from your hand or graveyard by paying life equal to its mana value rather than paying its mana cost.

Warhammer 40,000 Commander

If you cast a spell with {X} in its mana cost this way, the only legal choice for X is 0.

You may only cast a spell this way by paying the appropriate amount of life. You may not pay its normal cost and may not pay any other alternative costs. You may still pay for additional costs, such as kicker costs. If the spell has mandatory additional costs, you must pay those.