I was just running my high level roulette when this happened. Siren dashed up, no zombies had spawned yet, and I suddenly had the bind effect from the sergeants. it lasted the last bit of the battle where I couldn't move or attack at all, when a zombie actually grabbed me, it added a second debuff but when it died, removed just that second, the first one that appeared randomly didn't remove until we won the fight. Here is a screenshot:

Code:
https://pbs.twimg.com/media/BsD2sErCcAAdw6b.jpg:orig