Conduit of Ruin

If the first creature spell you cast in a turn has {X} in its mana cost, you choose the value of X before calculating the spell's total cost. For example, if the first creature spell you cast in a turn has a mana cost of {X}{G}, you could choose 2 as the value of X and pay {G} to cast the spell.

If the first creature spell you cast in a turn has converge, you can't ignore the cost reduction of Conduit of Ruin's last ability in order to spend more colors of mana.

The cost reduction can apply to alternative costs (such as dash costs).

If you control more than one Conduit of Ruin, the last ability of each of them applies only to the first creature spell you cast each turn, not to different spells; the first creature spell you cast each turn will cost {4} less.

The first creature spell you cast each turn doesn't necessarily have to be the first spell you cast. You could cast a sorcery spell and then cast a creature spell that would get the discount.

If there are additional costs to cast a spell, or if the cost to cast a spell is increased by an effect, apply those increases before applying cost reductions.