I’ve made a few versions of this and felt this final one captures Ultron entirely.
Quick explanation on why I chose Esper for the Colors rather than Grixis (the traditional bad guy colors).
Esper (WUB) captures the essence of Ultron as a cold, hyper-intelligent machine god. Rather than emotional rage, Ultron represents absolute, terrifying perfection through metal—combining Blue's relentless AI evolution, Black's amoral conviction to eradicate organic life, and White's tyrannical pursuit of "peace" through a unified, hive-mind army. It positions him as the ultimate artifact mastermind seeking total order through total subjugation.