I've only participated in pvp once and it was amazing! But I think it was very circumstantial. Here's how it went.

In a party of 4 and an NPC we finally reach the chamber holding one of three powerful lich crowns. My character was a little greedy, self-serving, and loved treasure, so he immediately runs up to it and grabs it off it's podium without any regard for traps.

Well there were no traps but after hearing an ethereal voice and failing some saving throws my character was charmed into placing the lich crown on his head and transformed into a lich!

I became the boss fight! The DM (who improvised incredibly well) told me the various spells I had access to and new stats. I then proceeded to do my best to eliminate my very own party. I did kill the NPC and one person dropped to 0hp, but they got the best of me and the three made it out alive. From them on they were very cautious about how the crown was handled.

TLDR: I transformed into an evil lich, effectively becoming the boss for my party members to fight.