If a permanent card in a graveyard has in its mana cost, X is 0 for the purpose of determining its mana value.
Whenever a creature you control with a counter on it dies, you may return another target permanent card with mana value less than or equal to the number of counters on that creature from your graveyard to your hand. Do this only once each turn.
in its mana cost, X is 0 for the purpose of determining its mana value.