In Nefarious Foes, I was fighting a team of Phoenix (green only), Silver Surfer (blue only), and 2* Daken (max champed). My own team consisted of Green Goblin (purple only), 3* Magneto champed, and Scarlet Witch champed.
I had already downed Daken, and Silver Surfer was down to 1500 health, while Phoenix was at full health. I used Scarlet Witch’s Reality Crush (2200 damage). It was recently patched to deal damage first, and then stun a random survivor. However, in this instance, it downed Silver Surfer and damaged Phoenix, but the stun did not take effect and the “Immune” word popped up, even though Silver Surfer was downed by the damage. Phoenix was the only survivor of the damage, but was not stunned.