The 12★ Units are really the biggest thing about Ultimate Amduscia. The Gix weapons are decent but not really game changers. The pet upgrades are a straightforward grind. The map itself is a straightforward Point A to Point B quest. So I’ll just talk about the Units.
To start off, I’d consider the baseline nowadays to be a Saiki set with two pieces crafted for HP, for a total of 200 HP, 35 PP and 60 ATK.
A bit of HP goes a long way nowadays, so I’m not a big fan of full PP crafts. Never know when you might need to carry an MPA of Axeon users in an Expert block through Profound Darkness and all. I’d say a good amount would be +250 to +300 HP including affixes. Crafting two Saiki pieces for HP gives some leeway to affix Alter instead of Flict to cut affixing costs.
Compared to a crafted Saiki set, the 12★ units are weak when used together together because they have no set bonus. However, their individual stats are great, so they patch up 2-unit sets very nicely.
As a reward for clearing Ultimate Amduscia with an S rank, the game rewards you with an Arm/Gix Cude
It’s a very decent unit. 50 HP, 10 PP, 30 ATK across the board. Trouble is it needs a rear and leg… but remember these things?
Good ol’ Ideal set. When used with Gix Cude, they give a total of 300 HP, 15 PP and 105 ATK. I’ll call this the Gixdeal set.
Gixdeal compares quite well to a crafted Saiki set, considering it’s much easier to acquire. Unlike Saiki, Gixdeal does not need crafting, and does not need 11★ passes or RNG. That makes it much cheaper and faster to get up and running. The extreme ATK also means you can trade off 30 ATK from Modulator for 5 PP from Spirita IV when affixing if desired, to save on affixing costs.
If the HP it comes with is a bit too much, just craft one of the Ideal units for PP.
I’d consider Gixdeal the free player’s new first upgrade after Hiei, before Austere.
Raystere / Rayser Set
There’s only one 12★ Leg Unit, the Leg / Circray:
No easy way to get it, but at 50 HP, 9 PP and 25 ATK, it’s a slight buff to the Austere and Kaiser sets. Nice to have if it decides to drop, but no sweat if it doesn’t.
Raystere gives a total of 240 HP, 39 PP and 85 ATK. A 2 PP and 25 ATK gain over the old Austere/Orbit setup.
Rayser gives a total of 39 PP and 115 ATK. If using Rayser, I’d trade off 60 ATK worth of Noble ATK for Noble Stamina. Alternatively I’d trade Modulators for Stamina IVs.
Rear / Gruzo Belra is an interesting 12★ TATK Rear Unit at 40 TATK and 15 PP. Unfortunately it’s held back by a lack of good Arm + Leg sets.
The three Arm/Leg unit sets available are the Double set, the Tagami set and the outdated Vento set.
A Tagami set crafted for two HP pieces would give 200 HP, 90 TATK, 30 PP. Trade 30 TATK for 5 PP by swapping Modulator with Spirita IV, and it’d be functionally equivalent to a Saiki with an extra Ring slot. Not a half bad option if only the Tagami set wasn’t so expensive.
Alternatively, a Double set crafted for one HP piece and one PP piece, would give 220 HP, 40 TATK, 45 PP. Not bad, but needs crafting on two units and a lot of TATK affixes to make up for low TATK. Gixdeal would make more sense.
With both Vento pieces crafted for HP, the combined set gives 200 HP, 80 TATK, 25 PP. Not amazing.
tl;dr the most interesting part of Ultimate Amduscia can be done in a single run. I still need to update my guides to recommend Gix instead of Ray, but that’s just a sidegrade really.