Ashad, the Lone Cyberman

Casualty was built as an aristocrat's mechanic: sacrifice a creature as you cast, copy the spell. Grafting it onto a Grixis artifact commander does two things at once. The first turns every nonlegendary artifact spell you cast into a potential two-for-one, but only the first each turn, so the copying is a tempo decision rather than a repeatable loop; you pick which artifact is worth feeding a two-power creature to duplicate. The second closes the aristocrat circuit that casualty opens: every other creature you sacrifice, not just the ones fed to casualty, grows the body a permanent step. The clever part is that a casualty payment is itself a sacrifice, so the copy and the counter fire off the same act. Point casualty at a token, at a creature with a death trigger, at anything expendable, and the artifact doubles while the 3/3 ticks upward. The color identity is the tell for how it's meant to run: blue and red supply the artifact density and copy synergies, black supplies the fodder and the sacrifice outlets. It rewards a deck that treats creatures as resources to spend rather than a board to protect, which is exactly the aristocrat logic casualty was written for, now handed an engine that grinds artifacts and grows a threat off the same fuel.