
Cromat is a five-color blank check: its activated abilities are mostly filler, so it mainly exists to unlock WUBRG and a beefy 5/5 body. Build it as a goodstuff/value pile that ramps into the best cards every color offers, protect your engine, and grind opponents out with raw card quality. Cromat itself can carry voltron damage in a pinch thanks to evasion, removal, and pumps, but it's the access to all five colors that does the work.
Prioritize the mana base above all else: add fast mana (Mana Crypt, signets, Arcane Signet) and premium fixing (fetchlands, duals, triomes) so Cromat and your five-color bombs land on curve. Then swap durdly cards for efficient interaction, fast tutors (Demonic/Vampiric Tutor, Mystical Tutor), and a tight wincon package so the deck has a plan beyond 'cast good cards.' Consider a compact two-card combo line you can tutor for, since Cromat gives you the entire card pool to find one.
The most-played cards for this commander, built from aggregated deck data (the Mythic Graph). Build public decks to seed it.
→ Infinite death triggers, Infinite ETB, Infinite LTB
→ Infinite colored mana, Infinite death triggers, Infinite ETB
→ Infinite colorless mana, Infinite death triggers, Infinite ETB
Combos via Commander Spellbook.
Same color identity (BGRUW), by popularity.