Meng Yu, Noble Traveler

Every time you cast a spell that shares a color
with Meng Yu, Noble Traveler and another
permanent in your field, you get a memory
counter.Creature spells cost {1} less for each
memory counter.
Whenever you cast an instant or sorcery spell
with converted mana cost equal or less than the
number of memory counters you can pay
{u}{r}, if you do, the spell gets rebound.