Usage of the に particle in this sentence The sentence reads > I understand the sentence as meaning "I'll establish a clear gaudy life priority" however I am confused as the the exact role is playing. I would hazard a guess its designating the source of the action but I'm not 100% sure. Any help would be much appreciated.

describes the manner in which the priority is determined (so it doesn't describe the nature of the priority itself).

So the sentence means: `I have decided on the priority of lives, clearly and flamboyantly`

Note that if you parse the sentence correctly, it doesn't mean "your priority in life" but rather "priority of other lives (as in who should live/die)".

It's an odd sentence (also in Japanese) - I'm guessing it's from anime/manga. It's probably purposefully odd to make an impact.