Halloween boss box

[Hellgamer]

So that box at top that shows energy and stuff changes to a version with pics of the bosses. after some bosses it shows a X above one and a number. How it works? what it shows u?

[Appeltjes]

What I'm thinking is a boss with a cross can't spawn anymore if you're the first to enter the portal.
Can anyone confirm my thought?

[Helicopter]

From what I heard, it's a kill counter. If it is, it's bugged. I recently killed Drakeula 2x and the counter still says 1.

[InternetExplorer]

It looks like a kill counter for me too.. after a game reset it shows my current kill stats. About the 2nd post im not sure if it works like that as i have killed paracelsus twice yesterday while i spawned and killed him when the event was launched.

[Cray]

Was wondering also.. Thought about a kill counter too.
Maybe it only counts for you if you deal the final blow? just guessing. I know that I defeated more bosses than shown in the counter.

[Sokpuppet]

What Cray suggested is correct. It will only add to your kill-counter if you deal the last blow to the boss.