Pyro Pete the Invincible (enemy)

Pete the Invincible is an "Invincible" raid boss exclusive to Mr. Torgue's Campaign of Carnage. He is a stronger version of Pyro Pete, and can be summoned by using the "Raid Post" found in his old arena underneath Pyro Pete's Bar, located in The Beatdown, once the main DLC quest-line has been completed. The mission to kill him, appropriately named "Pete the Invincible", is given by Mad Moxxi.

As with other raid bosses, accessing Pete costs 8 Eridium, and may only be done if nobody in your party has defeated him in the last 24 hours.

Behavior
When first encountered, Pete is introduced as "Pyro Pete the Invincible". Pete's basic method of attack bears little difference from the Vault Hunter's initial encounter with him as Pyro Pete. Pete will attack using his arm-mounted flamethrowers, either individually or both at the same time. He will either chase after the Vault Hunter while sweeping the flamethrowers back and forth, or take a position and lob 2-4 slow-moving, arcing flame projectiles at his target.

After approximately one minute has passed, Pete will stop and set off a nova-like Corrosive explosion. Although relatively low damage, this explosion will always result in the Vault Hunter(s) being afflicted with the Corrosion status effect. This status effect persists for an unusually long time, minutes rather than seconds, invariably long enough to kill a fully shielded combatant even with palliative skills such as Axton's Forbearance or Salvador's Asbestos. The only way to end the effect early is to use one of the two valves found in the arena, which will release a deluge of water that ends the effect, along with a number of spiderants or rats, depending on the valve chosen. Each time the valves are used the spawned enemies' level increases in increments of 3, starting from level 45 (25 in Normal Mode) and capping at level 66. Level increases are tied to each valve, e.g. if the rat valve has been used three times, using the spiderant valve will still only spawn level 45/25 spiderants.

After the explosion, Pete will be renamed "Caustic Pete the Invincible". His method of attack will remain unchanged, although his attacks will be acid-based rather than fire-based. After another minute Pete will set of a fire nova explosion, causing a fire status effect similar to the above, and switch back to "Pyro Pete the Invincible". This pattern of switching back and forth will continue until his shield is depleted.

Once Pete's shield is eliminated, he will set of a twin fire and corrosive nova explosion. At this point he will be renamed "Pyrocaustic Pete the Invincible", and his attacks will be both corrosive and fire based, e.g. his left thrower will shoot acid, while the right shoots flame. High damage dealt during this phase may dislodge his mask, revealing his face. Additional twin novas may follow, either at set intervals or in response to particularly high amounts of damage, such as from critical hits. This will continue until Pete is defeated.

Strategy
The battle against Pete is fairly straightforward, if particularly lengthy due to his high health and strong shield. Keeping a good distance between Pete and the player is vital, both to avoid his sweeping flame/acid attacks, as well as maximizing the small chance that the player will be outside the range of his periodic nova explosions. Axton's Sabre Turret or Zer0's Decepti0n hologram can be useful for this purpose, as like other raid bosses Pete will prioritize attacking these targets when they are present, rather than the player.

Management of the Burn and Corrosion status effects Pete inflicts must be done carefully. Immediately extinguishing the status effects using the nearest valve will cause the enemies spawned by each valve to level up. Rats or spiderants spawning at level 63 are a real possibility, and can even pose more of a threat than Pete himself. Allowing the corrosion or fire effect to last long enough for Pete to set off a second nova explosion is recommended if possible, as one use of the valve will extinguish both status effects, as well as providing appropriately leveled targets for getting Second Winds.

While avoiding the status effects entirely is desirable, it is also usually impossible owing to the large blast radius of each nova explosion. Players must be nearly on the other side of the arena for Pete's nova explosions to miss them, and if they occur near the center of the arena then it is unlikely that there is any safe area. A nova explosion cannot be avoided except by putting distance between Pete and the player; even the Phalanx Shield from Axton's Sabre Turret will collapse before the explosion is finished.

Although Pete uses Corrosive and Fire attacks, he is resistant to only Fire in his Pyrocaustic phase, while Corrosive deals significantly reduced damage. (i.e., Fire damage gives "Resist!" while Corrosive damage is merely reduced.) However, he is resistant to Corrosive in his Caustic phase. He is resistant to Fire in all phases.

Map exploit
Most novas can be rather easily avoided by hiding behind a scaffolding. This requires constant movement around the scaffolding, as Pete's normal attacks often can still hit the Vault Hunter. Some kind of regeneration (e.g. Decepti0n) is recommended.

Solo
Assassins are confirmed to kill Pete the Invincible in solo mode. Main challenge is lack of ammo, so constant top-up at ammo supplies is needed. A good alternative to gathering ammo is the Infinity pistol. Map exploiting is required, this can avoid most novas.

Glitch Method
There is also a glitch that allows a player to avoid his Novas entirely. When you first enter the arena there are two pillars/pipes to the right. If a player goes between those two pillars and jumps at an angle into the space between the wall and the pillar on their right side. They can then press jump rapidly and "climb" the wall. They can then get up on the ledge and hide behind the pillars when he nova blasts.

Sometimes he will jump up on the ledge following the player and get stuck there. If this happens the player can then jump down and he will not follow. Sometimes you will get lucky and? none of his attacks can hit you while he is up on the ledge in a certain position. You can use this method to kill him with any character and any gear just using the ammo boxes in the room to restock. The downside to this is that if he dies on the ledge you often cannot get back up there to get his loot after he dies.