1-st floor is for unwanted visitors. Two thiefs punished for their crimes, Altar with warning from wizard, to leave the place.

next room is spike trap room, but in reality spikes are illusion and everyone who jumps over them is doomed to jump into real spikes, or if you want to hurt your players a little bit you can move real trap before spikes, so that when they want to jump over they will make a step closer to an edge.

Then goes hall with statues and token of huge living armor, it'll ask players "what they were aren't able to see in tower" and the correct answer is "air", if answer is false - roll initiative.

There is also hidden room for players who are aware about unused space.

2-nd floor: is mages floor.

First players will notice air-fruit tree, if they will pop some of fruits concentration of O2 will increse, therefore they may become unconscious.

Next room is Mages portal, he uses it to avoid first floor entirely

Next room is his cabinet and living room. You may add some type of familliar to run the place while his master is outside. It'll try to block path to the roof for players, because it may be dangerous.

3-rd floor: is where the powerfull air elemental is captured. It'll ask player to release it. If they will, they will face anger of mage who's meanwhile returns to the tower using portal. Or they may try to fight it. Or wait for the mage and help with his experiment. Who knows.