I suspect there was a reason Blood Feud was uncommon and sorcery speed. This will be basically "Destroy two target creatures" more often than not, which is an utterly devastating effect, even more so at instant speed.

I'm willing to risk it for now.

Well.... it does cost six, in double-red and green. Instantly destroying two critters may be fair.

But wow would this skew limited. "Go creatureless or go home" springs to mind.

There are always dominant cards in any Limited environment. At uncommon, this will be dominant, sure, but it won't show up every game, especially due to the slightly fiddly colour requirements.

It was common, I thought. It aint now which yes, is a lot saner.

You're right, it did use to be common - hence my mentioning rarity in my comment. But I believe RIYW changed the rarity shortly before your comment.