That's odd, because the minute-long duration that ghoul already gets should be enough for the party to lay a serious beatdown anyway. Longer paralysis is a convenience more than anything.Actually, I flat-out banned the Create Spawn. With the Ghoul, it was the Paralysis that became a problem. At the lower levels, it was good enough, but as it progressed, it became a problem. When I allowed full levels of monster classes, the playtest group would simply land a hit on each monster and leave, in some encounters, and in others would just paralyze the monster and beat up on it.
..well, okay, if you change the powers around arbitrarily then yes, things may play out differently. I was assuming the class was actually as you had written it. That said, even with your Aranea Alternate Form, the web and poison are Ex special attacks and so have been available to a wizard for seven levels already by the time the Student gets it. Personally, I would rather have the humanoid alternate form ability the Aranea gets, as a much more versatile ability. Alternate form as a combat power is a pretty bad idea for a Student anyway, because it means pretty much all your other class features (as physical attributes of your previous form) go away, so an alternate form with utility applications is better.With the Aranea, I actually changed the Alternate Form(Humanoid) to Alternate Form(Aranea), replacing the Humanoid racial traits with those of the Aranea. This class was "taken" by another Student of the Weird in the playtest group, and was used to help immobilize creatures, to augment what the Ghoul-focused Student did. Again, this was much more effective at higher levels than the low levels.
My point remains: if your level 14 class feature is that you get a level 1 class feature, that's a bad thing.
Incidentally, another thought: the save DCs of monster abilities should probably be keyed to 1/2 the Student class level rather than the monster HD, or else they are never going to work on appropriate-level enemies.