Does paying an additional cost (like for Akshan, Mischievous) increase a card's cost for Yordle Explorer's effect, or does Yordle Explorer look at printed cost?

Ruling: Yordle Explorer looks at the printed cost only. Whenever a card refers to a cost, it's always the printed cost, not the total cost including additional costs.

Nuances:

• Even though additional costs are added to determine Total Cost during payment, card effects that reference "cost" use the printed cost on the card.