Power staff can't target if there is friendly-fire in some cases

[timid beacon]

I tried destroying mist censer with it (with skills 1-2), but I could not do it, because there was a hero nearby. I got the message: Friendly-fire only. But If I target enemy with the same skills, there is no such error. The game thinks that there has to be an enemy, but mist censer kinda is...

P.s. Sorry for the title, I initially thought that friendly fire was the issue, not the absence of enemies

[round bolt]

It is kinda both

You cannot use such skills on structures or empty tiles if there's an Ally next to them or the Magic Circle