The Mammon Machine is the boss guarding Knights of the Round.
I just kicked its ass too. Thank God I decided to go and finish up the Extra Battle bosses first. I got a Wizard Staff from Tyrant that allowed Aerith to get 2K per hit in Comet2. She was dealing 36K per turn. So awesome. I used up a few of my Megalixirs but oh well, I still have 4 more, plus 20 regular Elixirs. With W-Item now, that should be more than enough. I was worried there at the end of the fight when it said it was approaching limit since I assumed it would do some crazy damage technique that we could not survive, even with Wall or Shield. I was going to use my two Gospel Sparks but then Aerith was kind enough to win the fight before it could use the limit.
BTW, does Tyrant give any more rewards? First fight I got Red's Magic +30 weapon, second fight I got Gospel Spark and third fight was the Wizard Staff. Fought him about four or five more times and got nothing else. Was hoping to get a Magic +30 weapon for Cloud or Yuffie.
Speaking of KOTR though...um, is it supposed to kill me? I tried to use it on the Midgar Zolom because every fight up to this point the thing has just immediately ended the fight by ejecting my party. I wanted to try and kill it at last. Only I killed myself with my Sneak Attack KOTR.
Anyway, I too would love Dark Aeons. Hell, I'd love just a New Game + feature. That woud give me more incentive to keep playing the mod even after I beat the game.
So I think that does it for optional bosses, right?
Viridian Weapon - Beaten
Carmine Weapon - Beaten
All Extra Battle Bosses - Beaten
Al Kalm Traveler Bosses - Beaten
All Materia Cave Bosses - Beaten
All that's left is the final bosses, right? I'm pumped!!!
EDIT:
Wait, was it the Hero Medal you said earlier that I needed for the "secret ending"? You advised me to get a couple of them right? For NG+? I could probably do that. Be easier now with W-Item and stuff.
EDIT 2:
I now have 2 Hero Medals. I might go for a third but I can't see me doing any more than that. Don't be too hard on yourself - Nemesis is no pushover as a superboss for this mod. The fight is long and intense and you constantly need to watch out. Even with Ultra Spark's status ailments gone thanks to Ribbon, it will bring you down to just too little HP to survive Armageddon.
The new equipment I got from the Mammon Machine is helping a lot though. Mystile or something like that? Whatever it is, a lot of Nemesis' attacks miss now. The Minerva Band also seems to help Yuffie dodge it on occasion. Cloud though, he always gets hit and even if all he ot hit by was one Ultra Spark, it takes him to 100 Hp too little to survive Armageddon.
It's a pretty awesome fight. You have to keep on your toes.
EDIT 3:
Looking at this video
https://www.youtube.com/watch?v=WbGPS9bGmzoHe seems to do way more damage. That Cannon move only does like 2K or so on me, maybe 3. Then again, the fight seems to go way quicker for the LP'er than it does for me. Plus he has like, thousands more HP than I do. lol
EDIT 4:
Do you know if Nemesis gets stronger each time you fight him? Because holy hell, he will not stop killing Cloud now. I have not changed Cloud's equipment at all that I know of... Maybe one or two Materia I removed made all the difference but before Cloud could survive Armageddon, now he cannot. I'll have to look into this. I was trying to make my own video but it ended up being just an epically long failure.
EDIT 5:
Got my 3rd Hero Medal and made a video of it! A half-an-hour long! 6 GB! And that was half-sized in Fraps.... But yeah, long fight. I guess that just means I really suck. I don't know what made Cloud die easier on my third attempt but I remedied the situation by saying screw it to the Gigas Armlet. I didn't want to get rid of it because it had Str + 30 but I wanted to test out the Escort Guard. Well, no longer was Armageddon doing 6600 to Cloud. Now it only did 4900 or so. Plus losing 30 points of Str didn't hurt as much as I thought it would. Cloud only did like, 100 less damage per slash. So...yeah, gonna stick with the EG from now on.