Good for you don't play private server's if you don't know how they even work and what bugs can occur, also don't talk down on someone when they do know a bit more about it then you and you should possibly consider learning something from this.
As it would help you make accurate bug reports , don't just post this try recreate it and see , like what i did i found that it actually healed me in a FFA arena after about an hour of trying to recreate it.
So yes please just ramble on , i will post about how this bug is done a bit later in the day when i get time to make an extensive bug report, as you all my know there are a lot of bugs on private servers but if you cant give any proper feedback on how they are recreated or exactly what type of environment came into play please don't post trash threads like this, it wastes a lot of time.
TL/DR combat log is bugged and the ability randomly bugs out when bouncing to its final target.