Katara, Seeking Revenge
{3}{U/B}Legendary Creature — Human Warrior Ally
As an additional cost to cast this spell, you may waterbend {2}. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for {1}.) When Katara enters, draw a card, then discard a card unless her additional cost was paid. Katara gets +1/+1 for each Lesson card in your graveyard.