Specific orders - for 1P mission

I kept a strict log of three of my attempts at the 1-player version of this mission (you only fight seven, not 10 as the article currently reads). These are the orders that I got from the three attempts:

1. [Amateur Student] Lassar
2. [Apprentice Troubadour] Sinead
3. [Senior Ranger] Kusina
4. [Apprentice Warrior in Crush] Padan
5. [Apprentice Holy Knight] Collen
6. [Wise Fighter] Goblin Fighter
7. [Master Druid] Tarlach

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1. [Amateur Student] Lassar
2. [Apprentice Commander] Tethra
3. [Apprentice Ranger] Caitin
4. [Amateur Warrior] Trefor
5. [Master Executioner] Krug
6. [Wise Fighter] Goblin Fighter
7. [Master of Sewing] Arachne

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1. [Master Maid] Older Girl Next Door
2. [Fledgling Battle Alchemist] Heledd
3. [Master of Reading] Arzhela
4. [Apprentice Warrior in Crush] Padan
5. [Senior Vanguard] Nerys
6. [Wise Fighter] Goblin Fighter
7. [Master Marksman] Drone

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Due to the multiple appearance of certain NPCs in very specific rounds (just like in that Auction Event some months back), I have reason to believe that certain NPCs appear only in certain rounds. For example, in his appearances, Padan only came as opponent 4 and not before or after; same with Goblin Fighter in round 6 and Lassar in round 1.

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ADDENDUM: So considering the times I've played this solo mission out, this seems to be the specific order of the NPC talent type you face from my estimation (for the first six opponents only):

1. Random Mage
2. Random Alchemist
3. Random Archer
4. Random Warrior
5. Random Lancer
6. Random Fighter

For any of the above, a monster can replace any of the above types (I found Tethra instead of an alchemist on Round 2, an Incubus instead of a mage in a Round 1, and an Ogre Executioner instead of a Warrior on Round 4. As far as I can tell, there is no way to predict the final boss judging from the previous NPCs.

Applies in the 4 person mission as well, there is a strict order of spawns.

Learned from SPAMMING for transformations.

Yeah i've noticed that as well. Seems like the NPC spawn is too random to tell what the outcome boss is. I think the boss is randomed, because i've gotten easy and hard bosses sometimes when i was solo'ing the missions. But your 6 Type's theory sounds about right since ive noticed that myself (a different type of enemy) but never really pin pointed what it is.