Stronghold heroic encounter Beholders immune to soul puppet? [Solved]

scary

Last time I challenged the boholders I saw _A LOAD_ of "0" damage indicators like with Demogorgon in the 1st phase when its totally immune.
Is this a bug or a feature of the puppet or the beholders?
Or Tyrannical Curse, which was active at that time?

scary

AoE attacks apparently are applied to the rays of the beholders, too, but being no legitimite target, the resulting damage is indicated as "0". Found it by inspecting the combat logs.
So this is broken, effects should not be considered as targets, and the flood of "0" damages pollutes the screen unnecessarily.
Perhaps this applies to other monsters' features, too.