Dia, Force Unifier

Other multicolored creatures you control get +1/+1 and have trample and vigilance.

Unity of Forces — Whenever you cast a multicolored spell, scry X, then draw a card, where X is the number of colors in that spell.

Binding Synergy — At the beginning of your end step, if you control five or more multicolored permanents, you may search your library for a multicolored card, reveal it, and put it into your hand. Shuffle your library.