Interesting. A common "win the game" bomb, but jolly expensive. Turns any old 1/1 into a quick way to end the game... is that something you want all colours to have access to at common? If this was +0/+3 I wouldn't blink twice at it being common, but at +3/+0 I think it'd normally be more suited to uncommon.

I'd rather have all colors access to it if it is a bomb at common. I could perhaps up the CMC to 5, so then you probably wouldn't equipping it until turn 6 normally in limited.

What did worry me was the lack of artifact destruction in Eluim (which seems necessary being an artifact-heavy block). I added more artifact removal, or moved artifact removal over to common and other cards up in rarity (worked since I had a few cards with X at common).