Cyber Akuma, Tengu, Gil, Kefka, Duke...I could go on. These are annoying last bosses. The Warrior is easy.
I don't remember Kefka being hard at all, then again, I never really played the game without destroying each and every enemy in the game, going into the final boss at like level 99 and maxed out. Looks like I'm going to have to boot up the emulators
Easiest way to kill the warrior is to get him to come out, do a little damage to him, then allow yourself to get killed so you respawn back up on the top where you have superior cover and don't take damage from him, as well as having access to the vending machines.
When you respawn do NOT drop back down to the main arena, just stay up on top and chip away at his health.
I didn't face the warrior until I was level 33, so since you're at level 30 it sounds like you need to finish those side missions.
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Just consistent instant shield breakers then a random hit like any hits he does do through my entire shield and 90% of my health; all my weapons, mods, shields are level 29-30.
Stay in the middle where Lilith and Jack are under the force field, aim for his chest and ignore the rakks and crystaliks(?)- he'll never touch you. To be fair, I finished with Axton at level 38 and Maya and Krieg at level 37 (Axton did 2 DLC's Krieg 1 and Maya none). Sir Hammerlock and Tiny Tina's DLC are both rated level 30 so you would get normal XP for doing them, the other 2 would be considered trivial by now (but doing all 3 Slaughter Domes helps)...
The Warrior isn't bad, honestly. You just need to stay behind cover and he can't really hit you at all. Watch his tail, and other than that you're good.
Quick tip: Make sure you don't shoot at the Rakk's or Crystalisks. If you do, Rakk's will fly down constantly and attack you, making this fight about 5x more annoying. If you do happen to shoot one by accident or for a re-up, just take cover and ignore them and they will stop attacking after a shorrt while. Then all you have to do is move away from the Crystalisks every now and then and you're golden.
Honestly the Crystalisks are more dangerous than the Warrior...
Shooting the Crystalisks doesn't aggro the Rakks.
TC, there's a mostly safe area directly left from the central area (facing the spot The Warrior emerges from). There's a couple of ammo spawn stations and a big chunk of rock to hide behind when The Warrior and Crystalisks shoot crap at you.
Capcom won't see another damn cent from me until Mega Man Legends 3 is released.