People who have a champed Surfer routinely run him with Thanos because he can’t be stunned. Doc Ock now has the ability to be immune to stuns with tentacles out.
And yet, multiple reports have been made that Doc Ock is being stunned by Court Death when his tentacles are out.
I saw it in the Howard event only in this case I was able to stun him via 4* Gamora’s stun. Both as the primary target (3 turn component) and the secondary one (1 turn other character stun).
When I tried Talos stun (direct single target) it said he was immune and it only placed the secondary part which is the count down tile.
So it seems he’s affected by group / team stuns but not by direct single target ones.