Zenyatta, Wandering Guru

{u}{w}: Put a Harmony counter on target
creature. When damage is dealt to a creature
with Harmony counter, damage is reduced by 2.
{u}{b}: Put a Discord counter on target creature.
When damage is dealt to a creature with Discord
counter, that damage is increased by 2.
Only one Discord and one Harmony counter can
be at the battlefield at once.