I’ve tested this a couple times now and it seems to be repeatable for me.
When 5* Thanos is in front and downs an enemy Court Death activates properly and everyone except Thanos is stunned for a round.
However, if Thanos is not in front and an enemy is downed Court Death activates and everyone, including Thanos, is stunned for a round.
Court Death definitely seems hinky in execution. Like the OP, it fires reliably, but regardless of where Thanos is positioned, he’s only been receiving his turn maybe 20-30% of the time? The passive will fire, everyone but Thanos is stunned, but then it usually skips my opponent’s turn and my own turn before resuming the battle as normal. Whatever is going on, it needs some attention.
Court Death mostly triggers properly. But occasionally I’ve run into where it doesn’t. It seems to happen if there’s a cascade, and a critical happens and triggers.
Court Death also never seems to trigger from a KO from a Court Death.
Court Death triggers twice if 2 opponents are KOed at the same time.
If you make a match, and it KOs an opponent, Court Death happens, your turn ends (because you made a match), their turn ends (because they are all stunned), and it’s your turn again.
If I fire a power and KOs, Court Death happens, and my turn continues and I can make a match. I don’t think Court Death triggers again, for reasons I can’t think of. I believe that could be a bug.
I’ve been using Thanos more, and encountered another bug with Court Death. If I make a match that downs an enemy, but that cascades into a 5 star match, the Court Death is not triggered because I’m given an extra turn. This is happened a few times…and I wasn’t sure why Court Death wasn’t activating. Seems to be related to extra cascades/matches overwriting the activation. I’ve also encountered the stun problem. Very buggy power if you ask me…
A lot of passives that should activate after Match 5’s don’t seem to on occasion (From The Ashes being one and Daken’s Stroke Tile Generator thingee not being)