Xenogears - Amphysvena -Ramsus' Final Stand- (Boss)

It's time for the final bout with Ramsus as he makes one more desperate attempt to take out Fei once and for all. Before the fight, you're given a brief flashback that completely explains why Ramsus wants Fei dead.
Overview
This fight itself isn't terribly hard, but you need to conserve your Fuel, you'll find out why next video. Ramsus does a good job of making that really difficult, especially at the end. Equip Ether Ar's if you have them for your Gears, you'll need all the defense you can get.
Video Spoilers
So you find out that Ramsus was actually created by Krelian's technology, so he was not born a normal human. He was given Cain's DNA so that he could be able to kill Emperor Cain himself so that Krelian could forward his own plans. The mysterious girl you see in the video (you'll find out more later) reveals she's having a son...named Fei, and that he's "The Contact", which they then taunt Ramsus while he's still not born as now being useless because of Fei. Thus is the reason Ramsus wants Fei dead.
Stats
Fei: LV66 - Rose Tabard, Dark Helm, StaminaRingS
Ether Ar +3, Ether Ar +3, Frame HP30
Citan: LV65 - Yamame Sword - Black Leather, King's Helm, AntiEthStone
Kishin Sword - Ether Ar +3, Ether Ar +3, Frame HP30
Billy: LV62 - B&J M10 Gun - Dark Armor, King's Helm, EtherDoubler,
G-M686 Gun Ether - Ar +3, Ether Ar +3, Frame HP30
Strategy
So what makes this really tough is that Ramsus can do his Demiser move, which reduces everyones HP to 1. That is pretty ridiculous, and puts you in a tricky situation. It's random, though I think it's always used near the end, and sometimes near the beginning.
Ramsus only has 28k HP, so Booster and slam him with Fei's System Id and everyone elses' T+S Deathblows.
That's about all there is to this fight. You should know the drill by now. Frame HP heal if needed, hopefully you don't blow way too much fuel.
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[@Dhalin]

Goten X... one of the coolest looking attacks in the game, non stop.

[@kinh0t]

+Dhalin i think its a shit ugly move

[@Joshua.670]

Oh no, feis mom is named karen!!!!

[@mmacionk2]

This Wave#3 Demiser is a real pain in the ass, but Miang's Wave#4 is even worse

[@ArmyGuyDan]

Kinda Sucks Bladegash wasn't playable for this battle

[@davemarsh7085]

why dont i remember fighting this guy?

[@KvngNothin]

Oh God ._. Instant 1 Hp?

[@TryckSpot]

Yep. This was by far the hardest part of the game for me. Especially cuz it's immediately followed up by a fight with Miang. Spent so much time charging and healing.

[@tek512]

@@TryckSpot Should've just used Chu-Chu. Raising her stats in her normal form also raises them in her giant form, and she gets some of the most powerful healing abilities in the game. At max stats, the sheer damage of each of her individual hits is comparable to using Kishin, so her lack of combos isn't an issue.

[@tessatessa3894]

Any tips? Miang kicked my low hp ass.