Gellidorne, Pure of Mind

Whenever you cast Gellidorne, Pure of Mind, target player must counter it if able. If he or she does, search your library for a card named Gellidorne, the Ageless and add it to your hand. Then, shuffle your library. Until end of turn, creature spells in your hand with converted mana cost 10 or greater have affinity for creatures.
{4}{u/b}{u/b}, {t}: Target player loses X life, where X is the number of creatures they control.