Sazed Harmony Incarnate

Flying, hexproof from multicolored
Whenever Sazed Harmony Incarnate deals
combat damage to a player, it deals X
damage to any target, target play
draws X cards, and you gain X life,
where X is the number of different
color pairs among permanents you control
that are exactly two colors.
Is Niv-Mizzet, Guildpact