Mechanics:
Chain quick kills in succession to get movement speed bonus. What I do is run around a large group in a clockwise circle, and then run through the middle of the group and then do a counter-clockwise circle around them. This causes them to all group up tight and is classic Robotron kiting. Throw a grenade on the group and you'll get multiple speed boosts. You want to have at least 7 movement speed bonus on the final boss to be able to outrun all of his abilities.
Important things to note:
- The boss has a white (health) bar and a blue (shield) bar.
a.) Panzerfausts and grenades take down the blue bar. You should stick to using Panzers exclusively for this.
b.) When the blue bar is recharging, the boss is immune to panzers and using them on him at this point will not affect is shield. It will keep recharging until it reaches full.
c.) If the boss is powering up his ultimate attack (glowing orange) and recharging his shield, you can still stun him by firing the rocket right as the shield fully recharges.
2.) The first boss does his ultimate attack at 50% life missing.
The 2nd boss does his ultimate attack every 30% life missing.
The 3rd boss does his ultimate attack every 20% life missing.
a.) The first boss requires 1 panzer, the 2nd requires 2, and the 3rd boss requires 6.
b.) If you don't interrupt the boss during his charge-up phase, the 1st boss will take half your life, the 2nd boss will take 2/3 of your life, and the final boss will instant-knock you.
3.) The supply boxes around the arenas resupply their loot, changing the contents even if the box hasn't been looted, every 30 seconds.
a.) Panzers and Self-AEDs drop from the boxes, as well as grenades and ammo, though you won't need ammo after your first few kills.
4.) In order not to miss your panzer shot, you have to stop moving while looking at the boss, and wait a second for the panzer to "lock" onto the boss, otherwise your rocket will almost-always miss.
5.) All players should loot ample amounts of Self-AEDs for the final boss, since it's less mechanically-forgiving during the ultimate attack charge-up. Typically, if you don't want to rely on Self-AEDs, you need to hit him 5 times with rockets and hold off on breaking the shield until the ultimate charge-up occurs every 20% life, and use the last rocket to interrupt him.
a.) If everyone has a bunch of Self-AEDs, you can ignore the ultimate and just eat the attack and then self-revive yourself.
b.) Self-AEDs spawn en masse from supply crates on the final boss.
c.) You can jump to avoid the horizontal laser beams from the final (G-Toilet) boss.
6.) Bosses face whatever player they're about to cast their next laser attack on. If the boss looks at you, run in a straight direction adjacent to the boss and you'll never be hit by his attacks.
7.) The Lynx is cheap and you can solo the final boss with it, and outrun all of his abilities with 7 movement buffs. I bought the lynx 6 times in the fight above because 2 of my teammates were dead.