Hi. Regular enlarge person isn't as good as a full size increase according to the table in the bestiary guide. As a first level spell though, that's to be expected. What I want to do in game is`research a new, higher level, "improved enlarge person" spell that really does increase a full size category with all benefits and negatives that goes along with it, and that can be made permanent. There's not a lot of rules for spell creation, mostly just the part about level and research cost. What would you guys consider that spell to be levelwise? Just curious, might help with my DM if I have a suggestion and reasoning beforehand.
Enlarge person and polymorph spells probably shouldn't do that in PF, there is a clear cap on the abilities that polymorphed creatures get, only a part of their ability bonuses and natural armor bonuses. A full size increase will be better than the old polymorph spells, it seems a very bad idea in short. Making it permanent worse. The game is already a bit too much of a rocket tag game at high level, expect opponenets to do the same thing for a 10,000/12,500 gp reduction in wealth they carry. That said :
A similar function spell might be seen in monstrous physique II, allowing a large monstrous humanoid it seems a bit weaker and only personal, I'd settle for a 5th level spell as appropriate level, making it 12,500 gold to make permanent. Maybe 4th level if it adds the Giant Template instead, costing 10,000 gp to make permanent.
In my (3.5) game I have a 6th-level spell called enlarge monster that grants the full benefits of a increase in size of one category. It also works on all living monsters, not just humanoids.
Oh, I don't allow permanency to work on enlarge monster.
They have precedent for a permanent enlarge person (Viorian Dekanti in Rise of the Runelords). HOWEVER, I'd say look at giant form and get that permanent.