I partially agree with Sarthra. Haunt is terrible for anything except the Baron (and is unneeded even then). However, I would replace it with Traumatize. I'd probably even replace Terrify with another Traumatize. Stun is gud.
For the benefit of Highfire and other people who play this game on Easy, Nostalgia is the third boss of Zone 6, which is only available after completion of Zone 5 (surprise, surprise) on Challenging or Heroic difficulty.
I soloed Nostalgia (successfully) for the achievement using an electric-build Psycho on Challenging, which to my knowledge is identical to Heroic except for that pesky time limit on moves. My build was pure Instinct, both in terms of attribute point expenditure and equipment selection, rendering Free Will absurdly effective as a defense against Nostalgia and source of healing. With a more moderate build that may not work.
My skill breakdown was as follows (level 26): Free Will (4/4) x2 Shock Therapy (3/3) x3 Electrical Storm (4/4) x1 Traumatize (2/2) x2 Charged Blood (5/5) passive Tenacity (4/5) passive
For Equipment I used Mayor drops with a side of Council Member where the instinct bonus was higher and Poseidon's Fury [AKA mah BOOM stick], which is a rare drop from something late in the train zone or early tunnels (maybe Clemons).
As for Nostalgia himself, the fight comes in a few significant stages. In the first, he will constantly hit you with damage over time effects and then use an attack that grants him a special effect called "Venomous Intent", which multiplies his DOT effects by a factor of fifteen. DO NOT LET HIM DO THAT, you can dispel his DOT effect with Free Will and should do so if possible. He also has a rather pesky massive damage buff, which I routinely countered with Traumatize, dealing about 750 damage in the process. I made a habit of stunning him on those turns when Free Will lapsed to prevent him from taking advantage of the single-turn opening necessary to reboot my shield. The second phase is a bit trickier. Nostalgia will use a move that confers a buff called Earth Titan, which provides him with a massive defense bonus. This phase should keep you focused more on self defense, while trying to whittle away at his health where easily possible. This phase simply takes time, be patient. After a sufficient amount of time/abuse/swearing Nostalgia will become as bored as you are and dispel Earth Titan, bringing us into his final stage. Nostalgia's third stage closely resembles his first, except that he develops the irritating habit of blasting you with an ice projectile that drains his entire stored focus and deals damage dependent upon the amount of focus used. At about 70 focus, this move broke a fresh shield and dealt another 700-ish damage on top of that. Anything higher than that killed me outright. Traumatize will help keep his focus low and Haunt would be handy if you can spare the slot. When Nostalgia falls below a certain threshold (call it five or six thousand HP) he'll heal himself for 10,000 life, making retrograde handy for this fight, but not entirely necessary if you're persistent (I did that one the hard way... it was not fun).
Build-specific advice for RKO: Wraith Form- Good clean fun in most fights, it will often get you killed here. Nostalgia demands to be assessed on a turn-by-turn basis and your average damage per turn will likely be higher if you just ditch Wraith form for this fight. Terrify- I do not care for most of the dark Psycho moves, and this one seems redundant in your build. Your healing should be provided by Free Will (500hp/turn with good intellect bonuses) and you can get a much larger damage output from Shock Therapy. - The ability to make Nostalgia miss turns is handy throughout the fight and absolutely necessary if you plan to win the fight without Retrograde in your lineup. Throw in a Traumatize or two to make sure that can happen. The focus damage is nice, the defense bonus is not. I often used the turn where he was stunned to refresh Free Will or use Electrical Storm to start my focus recharging. - The other stuff looks pretty good and throwing in an extra Free Will or Retrograde would likely improve it, but you absolutely MUST have Traumatize in your lineup.
This may have gone a bit overboard, but you should be able to defeat Nostalgia with reasonable certainty now. Don't worry about boss #4, she's a pushover.
I realize this is a very old post, but I had to bring this up.
I just beat Nostalgia using a hydraulic character lvl 27. I skipped phases 2+3. This is how:
So I used my points primarily in the str attacks, but also had the 2 move stun in my build. As soon as you get Nostalgia to about 80% damage, stun him, and blast away through his health. I do about 4000-6000 per attack so this allowed me to do about 150000 damage before he could do anything. This brought him down to 10000 life about and I used the Slam ability, luckily stunning him again, and finished him off with a few more attacks. He did not turn on the shield ability, nor use his super powerful attack with focus. GG in 2 minutes. Hope it works for you!
I was a 25 Hydraulic and used my abililty Wreck, Demolish, restore, stiffupper(this a a passive combat effect), and flash freeze (all fully upgraded) attack him with Wreck then use Flash frezze.Keep attacking with demolish and wreck until he get up, use flash freze agian and keep attacking. he wont use his sheild and ever time you get flash freeze use it . Focus all ability points on stength (mine was 552 with the wepons Platinum Baton, Royal Grips, Imperial War Helm, Riot Armor, Royal leggings, and Imperial Marcher)it was an easy 45 second match hope it help
no need to make level 30 or brag about your sonny. If you're biological just use crystalize. The enemy can't do nothing for 4 turns. The delay for break is 4 turns. see the trick? you can also put crystalize two times on the skill slots!
i beat him lvl 26 challenging, but i got super-duper-duper lucky :O. but i beat him with teammates. using speed bio. when i crystalized him and then it wore off roald did the ability in which he stuns his enemy so then i used speed bio and killed him the next turn. he never got to use earth titan
Thats the one complaint I have with psycho...only one stun that makes it harder to kill your opponent, and then it is rare for your allies to stun as well.
