Known issueFixUpdated · 4 replies on Steam
Booster Pack Heroes: Frenzy Gamebreaking Bug (Workarounds)
Short answer
No confirmed fix yet. Players suggest: Thanks for reporting it, will be fixed in the next update.
The problem
If you have a frenzy buff (or multiple) while the animation for the second phase of the boss is happening, the buffs will become permanent. Also I don't know if it's intended but stacking multiple frenzy buffs is too strong, with 4 you can kill the last boss easly even without the bug
What players suggest
Thanks for reporting it, will be fixed in the next update. Stacking frenzy is a lot of fun to be removed, so I'll keep an eye on how easy it is to accomplish that and maybe change some %s.
Throw in an enemy with thorns that hurt the tower if you try to attack it with the cursor.
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Source: original Steam Community discussion. Quotes are shortened; all credit goes to the posters.