71 hours later, I finally saw credits on my ending. It was… kind of an amazing ending with a twist at the last 1 second that honestly shocked me into laughing out loud. Definitely an ending I’ve never seen before, at least!
The final boss is hot bullshit, but he’s beatable with some tips that I think I have developed and I’m happy to share. Note that this worked for me, there wasn’t any good guides out there that I found, so this isn’t like tried and true, just what worked for me. I’m going to spoiler the rest of this, rather than cherry pick what I do and don’t spoil, so if you are here you are looking for specific advice on the final encounter in the story, after the Hanging Gardens dungeon.
First, a note - I hadn’t seen a Game Over screen until like hour 60 or so when Denem was knocked off a cliff, and I got hit with TPK, haha. However, after the Game Over, you are offered a few choices, if you didn’t know. You can retry the battle from the beginning (helpfully from the squad setup screen so you can assign new skills, items, and etc. for the battle you just lost) or you can reload from “mid-battle” which just means the game gives you back control and let’s you use the Chariot to roll back time if, for instance, you just need to not stand Denem on the edge of a cliff to pull off a victory. Anyway, this is true for the final boss as well - if you were close, don’t rage quit, is my point. Restore from mid-combat and roll back to make a few minor tweaks to your strategy, see if that gets you over the finish line.
Okay, onto the detailed tips.
First, there are two phases - the first phase you face off against a powerful foe, but his greatest asset is he summons 12 doppelgangers of your squad. That’s… obviously less than ideal, and they will prove far more formiddable than any foe you’ve probably yet faced, geared up and max skill’d as they probably are at this point. He also uses a nasty skill I have seen earlier in the game called Risk Management - he’s immune to damage if he’s near allies within 2 squares (the damage is shunted off to them instead). This seems to proc at the start of the battle every time, but usually not EVERY turn, so like when fighting dragons or Golems you just want to wait and unload your attacks on him when his defensive proc doesn’t trigger. For me that was the second round every time, if it DOES proc on round 2, I’d roll back and make new choices to generate a new RNG to get it to NOT trigger on his turn starting.
Meanwhile, don’t take any actions on your first turn. You can’t really hurt him while Risk Management is up anyway, and all you’ll be doing is spreading damage around his units and then it’s their turn and they’ll surround and murder a few of your troops. Instead, move up a little for melee units and stand still for ranged/spellcaster units. DO NOTHING more than move. Hopefully Mediates will proc for you, if they don’t feel free to use an herb (nothing more you can do), but by not taking any actions this first round, you ensure advantage on the initative bar the next round when hopefully Risk Manage didn’t proc. Then, you can alpha strike him and if you can kill him in round two before your allies have at all dropped, you’re going to be in MUCH better position for the final battle.
If you can’t kill him in round 2, he’s going to probably drop Damnation which is a field condition that prevents all resurection. There is a skill Clerics have that removes this - it’s IMPERATIVE this either not proc OR you have a cleric on hand to remove it. I found having a healer helped keep my troops fresh when his turn came up using a huge Major Heal II spell that granted like 390 health to my front liners.
All you have to do in this first phase is bring the enemy to critical health. If you’re guys were able to surround him, using pincher attacks in particular, and wail on him and bring him down, the battle ends and it’s onto phase 2, or what I call “bullshit”.
Phase 2 will start with all your units in a huge ring, if they were down in phase 1 they are still down here, which is why it’s important to keep everyone alive for this part. This guy, the big bad, is going to teleport around the map, hitting like a fucking truck, and summoning spells that hit most of the battlefield for big damage, and he’s going to like to go every 2 or 3 turns your characters take, when you are down to only a few remaining troops. Having your entire roster helps this a lot, let alone the fact more hands mean more full-health heals and ressurection stones bringing characters back up.
Stock up on items that fully heal and ressurect, but everyone should have one item that either weakens, spoilspells, or breaches so you can try to get all three on this turd. Spoilspell is really nice because it keeps his summon spells from dropping everyone in a single cast, for sure. In fact, many times I survived two castings in a row and I thanks Spoilspell for that. Otherwise, getting to him can be a pain as it’s a big open field and walking towards him when he teleports around can be tough, so I was moving my units all towards him and keeping them somewhat together - this just kept him near us as he wants to attack. Stunning him is possible, though I only saw him stumble like… once. Weaken and Spoilspell are your friends.
Also, Dark Mage hurts him the most from what I could see. My Water Oracle would do like 70 damage with a spell while my Dark Warlock would hit for 225-240 with Word of Pain III. Whenever he dropped, I’d bring him right back up and if Meditate dropped when his turn came immediately around, he’d cast it again and if he dropped, I’d repeat that process.
Otherwise once we got close enough to surround him we’d just hammer away on him, sometimes doing only 25-75 damage but then getting a few 50 point pincer attacks in, and somtimes melee attacks would do like 150-200 damage. Honestly I have no idea, maybe his defensive stats change based on which summon he just used? Also super bullshit, many of his summons deal a ton of damaga AND MP damage, so my guys with 100 mp would have like 3 left when their turn started. Keep your casters away from melee clusters, it’s a tempting target for him to hit them and that leaves your weaker casters alone.
I think that’s about all I got - it was a great fight once I wrapped it up, weirdly I wiped two times in a row and the third time no one was down when the fight ended except the cleric, but he was fine after the battle.
Good luck!