Lvl 17 character to beat a lvl 17 abjuration wizard in PVP

Im running a campaign thats 17-20 and one of my players ended up making a beast of an abjuration wizard. Two of my players did a friendly PvP out of game a couple of times and the ab. wizard has been damn near impossible to get down to even half health because if invulnability. So now im trying to make a pc that will bring him down. I was think martial focused twilight cleric because of antimagic sphere. What do you guys got? Throw me your hardest hitting builds that will take this PC out.