At first I thought Sated Devourer was simply non-functional during his Q, as it didn't make it go off in two hits, nor did it even double up on-hit effects every other auto. I was wrong! Seems it DOES apply on-hits, just to him rather than his target! And look, it's not even an execute!
And hey, redbuff refreshed after killing me!
I made this video on the PBE, but the same thing seems to be happening on live.
Edit - This did reduce my bounty!
Edit two - I'm working on an in depth video about this bug, and a ton of others with Mordekaiser and items. While doing so, I figured out Xin Zhao can also hit himself during his Q against inhibitors, but nothing else. I'm assuming this is because inhibitors proc sated, but not Mordekaiser hits himself off anything during his Q.