The Charmed Elevators

Floor #05: Defeat three enemies.

Floor #10: Defeat ten enemies.

Floor #15: Drop (and pick up, if desired) any two items and defeat five enemies.

Floor #20: Beat the boss.

Floor #25: Drop (and pick up, if desired) any two items and defeat eight enemies.

Floor #30: Drink two Potions of any type, but the same type for both, and defeat eight enemies.

Floor #35: Drop (and pick up, if desired) any three items, defeat eight enemies, and perform three attacks at nothing.

Floor #40: Defeat the boss.

Floor #45: Defeat eight enemies, perform five attacks at nothing, and read any two books.

Floor #50: Defeat ten enemies and do nothing for five turns (Circle + Select).

Floor #55: Defeat eight enemies, perform three attacks at nothing, read any two books, and do nothing for five turns (Circle + Select).

Floor #60: Defeat the boss. After, let the Founder appear and stand a bit away from the elevator and hit him once, then the elevator will unlock. This is easiest done the moment he appears with an area attack.

Floor #65: Something to do with the Founder.

Floor #70: Change into a Leblanc Syndicate uniform. There is a book to do so, and the Founder can also do it for you. Note that the Founder will warp you outside the tower after doing that, so, for that method, stand on the elevator so you'll change, the elevator unseals, then you can immediately go. To be more specific, stand on the elevator and wait for the Founder to approach. Attack him - preferably via an area attack - and you'll turn into a Goon. Then press X (hit nothing) and the elevator disappears.

Floor #75: Drop (and pick up, if desired) any three items, throw (and retrieve, if desired) any three items, defeat eight enemies, attack at nothing five times, and do nothing for five turns (Circle + Select).

Floors #77-#79: On these floors, you'll be able to find the Founder, whose function normally was to warp you out of Iutycyr Tower. However, he has a vital purpose by the time you hit Floor #79 (actually works as early as #77) - in lieu of warping you out, he'll warp you to Floor #77. From there, he can warp you to Floor #80. So, basically, you need to stick around on #77 for a while.

Floor #80: Defeat the boss.