Scarred witch doctor has the correct (errata'd) text for fierce intelligence:
"A scarred witch doctor treats her Intelligence score as 2 points higher when determining the highest level of spells she can cast, the number of spells she can cast per day, her spell save DCs, her number of spells known at 1st level, and any effects of her hexes determined by her Intelligence. BONUS:STAT"
But does not receive bonus spells per day properly. I created a level 3 half-orc scarred witch doctor with 19 INT (which should be treated as 21), but only received 3 spells per day instead of 4.