How do I beat the end-boss in Borderlands?
I just recently completed the game so it's still fresh in my mind. There are three places you need to hit the end boss. The best way to do that is from behind the arch you came into the map. I've tried to fight from behind the pillars in the middle of the field but died...
Useful weaponry: * Longbow grenades (The only ones you can hit it well with) * Sniper rifles (I think shock did pretty well) * 11001010 cannon or what ever the name was exactly (infinite ammo = very handy towards the end) * Rocket launcher
You can see a pattern here: distance distance distance.
Alright. The first thing you have to target are the glowing purple orbs in the tentacles. As long as the tentacles are around they shoot missiles at you in periodic intervals. And let me tell you those hurt! Only weapon suitable for this is the sniper.
Second thing is the tongue. The boss has a vertical mouth. Once you've destroyed the tentacles this thing starts opening on occasion and a tongue shoots out trying to hit you. You have to hit that. Best way to do it is the sniper gun. If you manage to time it right you can use the 11010101 or RPG.
When you have destroyed the tongue the eye part begins. Occasionally the eye opens and shoots a bright beam at you. When it does that the eye becomes an easy target. You can hit the eye in between attacks too but it requires rather good aim. From time to time the tentacles will grow back again and you'll have to shoot them off a few more times so it's important that you save enough sniper bullets for that and use the slower ranged weapons for the eye.
At the start of the fight "The Destroyer" has some purple tentacles that throw explosive spikes. Destroy these tentacles as soon as you can by shooting the glowing orbs near the base of each tentacle. For the rest of the fight it's best just to use a pillar for cover and shoot it in the eye. It takes a long time but he's basically a bullet sponge.
Whenever tentacles show up, shoot them on the orbs. When they're not around, hide behind the pillar and shoot him in the eye. Use one of the super-powerful scoped pistols until you run out of ammo, then switch to a scoped rifle. Accuracy is important since hits to places other than the eye and the tentacle orbs don't count. Be patient — it takes a while.
Aim for the mouth. You can even shoot the mouth when it's not open, as long as you aim in. Break a tentacle by shooting the glowing, violet cyst, but you should save these to fuel any on-kill skills that you may have or to get a Second Wind when you're fighting for your life.
The Destroyer is not weak to elements, but only weak to critical hits.
Comparison: Shooting at the mouth
Shooting at the eyeAs you can see, I run out of shotgun shells and can't even kill the Destroyer if I shoot it in the eye, but this is not the case with the mouth. And in contrast to Kempeth's answer, I don't keep my distance; I try to get as close as possible to minimize the amount of projectiles missing.
What about safety? The Destroyer continually attacks and its attacks include firing missiles that rain down from above and that stick to what they hit, exploding a bit after landing. You're either agile in the open or edging, trying to find a covered angle in which you'll be safe to plink away until you have to move from the spike missiles.
Besides, ignoring the money loss, the bright side is that you have indefinite respawns, and if you die, you'll respawn in front of the Destroyer. You can fast travel out from the Vault, but if you leave and come back, the Destroyer will be back at full health. So, you may want to worry more about using ammo fruitfully.
Borderlands speed-runner (Speed Demos Archive) Youkai gives advice too:
He says that breaking the tongue opens the mouth. Then he throws in his explosive bouncing betties which deal enough damage for the Destroyer to go through the stages of "clawing out" the portal, during which the Destroyer does not attack.
I was playing through playthrough 2 up to this boss and didn't even bother hitting any of these areas. I was solely focused on hitting a tiny sized weak spot (just between the eye and the mouth using the XX Fearsome Gamble 806 power with 200% critical damage). Each shot hits it for pretty much 11,000 damage per shot from a distance with Siren with the 25% critical hit percentage skill thing. I don't know if this is a lot, but it still takes a while. I only have about 10 proficiency with it, so I'm waiting for it to increase.