disclaimer, full merc solo main bias included.
out of all of the bosses, this one disappointed me the most. i think e8k8 mithrix is lacking because the fight itself was not changed in any way to make it meaningfully harder. the fight oozes with artificial padding that makes him take forever to kill since even e1 gives him the shields. as mercenary imo the name of the game is staying the fuck away from him since unlike every other boss in the game, new mithrix doesnt stop teleporting. there are hardly safe times that i have found besides post slam to actually fight.
...so i got my royal capacitor and stood on top of the pillar and cheesed the fight all the way from phase 2 and on. and to be quite honest, why is this still possible? i imagine many other characters get up there without too much difficulty as well. for such a hyped up rework i would think this basic cheese wouldnt work anymore.
i was surprised to see the community not like voidling or solus wing, but as merc i love them. i have to strafe and cycle cooldowns according to their attacks so i dont instantly die, but with mithrix he just ends my eviscerate early which makes me very one shot-able. and phase 4, while most certainly easy for other characters, is still beyond being worth running up to as merc so once again that pillar and royal capacitor will be your best friend except this time he has shields and heal drones to prolong it.
overall i am shocked this boss and the HC secret boss were developed around the same time. i feel like the best strategy for this boss is to sadly not engage with it at all as everything he does is fuck you damage at fuck you speed with fuck you health and fuck you shields that prevent you from cashing out the damage you earned. at least if the shields were gone, i could risk myself by blitzing him. if the boss is WAY too free with a certain strategy/not hard on some characters but actually dumb to fight when you engage with it "normally", its a questionable fight.