Fix bosses 'fake animations'

It's a bug

 

There have been a number of boss-related issues, during these years, which have been investigated and fixed (some with more success than others). The fake boss animation problem is likely the side effect of one of our latest fixes, which solved a specific case of boss freezing, that was ironically caused by faulty error handling.

While I can confirm that this will be investigated (it has already been, partially), I can't give a timeframe for its fix. Monster control/aggro logic debugging requires both client and server analysis, and while sometimes we've been lucky and spotted the issue pretty quickly (as was the case with last year's Banish hotfixes, if we include those in the boss problems category), most of the times it's a lengthy process.
To give a bit of insight (or more precisely, speculation), the server is probably deciding that a specific skill/attack should not apply, after it has already broadcasted its activation to the players clients, which then desyncs the next skill/attack procedure. Figuring out where exactly that goes wrong will be the long part.