Logic Knot

You can exile cards to pay only for generic mana, and you can't exile more cards than the generic mana requirement of a spell with delve. For example, you can't exile more than seven cards from your graveyard to cast Treasure Cruise unless an effect has increased its cost.

Delve doesn't change a spell's mana cost or mana value. For example, Treasure Cruise's mana value is 8 even if you exiled three cards to cast it.

To cast Logic Knot, you choose a value for X, determine the total cost, then pay the total cost with some combination of mana and exiling cards.