There are four ways I know of to get your intelligence increased as a Wizard:
- Levelling to get stat bonus (Untyped, 5 by level 20)
- Headband of vast intelligence (+2 to +6 enhancement bonus)
- Crimson Sphere Ioun Stone (+2 to +6 enhancement bonus, stacks with itself only)
- Tome of clear thought (+1 to +5 Inherent, permanent, same as 'Wish')
This limits a wizard to a 'measly' maximum of 36 intelligence: base 18 + 2 (race) + 6 (headband or stones) + 5 (levels) + 5 (tome).
What other ways that will stack with these can a Wizard increase their intelligence?
Polymorphing (or race changing) is semi-acceptable, but this is not a ideal solution as a permanent bonus is preferred without changing race.
Best Answer
Become a Lich
Pathfinder Lich Template
You get +2 to Intelligence for forsaking your humanity.
Mind you, this means you value your own humanity at 4,000 gold and are willing to pay 120,000 gold.