Okay, so I think I have a perfect occasion tommorow to make Thartler kidnapped by the Necro-Pterodactyls and set in the cage. The Spire is the place filled with lots of undead and skeletons, and it's divided by floors.
1st floor, also the biggest: Nothing, except for four statues. I think of it as the entrance room.
2nd floor, with Rotting Swordsmen, Rotting Pikemen and Rotting Archers (Yes, they're zombies. And yes, they have weapons)
3rd floor, with Armored Bones and Boney Horsemen.
4th floor, with three statues. Those will be a puzzle of sorts.
5th floor, with the Tanks from Left 4 Dead (*Yeah, don't question my logic*)
6th floor, where, depending on speed, you might either retrieve an alive Latias or have to fight an undead version of it (However, this only means Thartler will be floor higher)
7th floor, where the you have to fight the Necromancer, Possessed Latias(If Thartler was retrieved early) and Sorrow or Regret. Sorrow for Possessed Latias, Regret when you find him trapped. Regret is basically the skeletal version of Expert Ranger, while Sorrow is a ghostly clone of the Commando Thartler, the Dragon Hunter.
8th floor? Who knows, maybe a bonus fight?