Veteran Adventurer

If a spell has a cost reduction based on the number of creatures in your party, no player may attempt to change that number after you begin to cast the spell but before you pay the cost.

Several cards have a cost reduction based on the number of creatures in your party. To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions. The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.

The ability that adds creature types to Veteran Adventurer applies in all zones, not just the battlefield.