I don't know if you're planning on updating the witch doctor, but here're the notes that I made on some of the powers. They're house rules for me, and they're my suggestions when you're doing any potential revisions.
Taste of Mojo - Utility 6 - becomes daily; you may know the value rolled on the saving throw before deciding to use the power
Curse of the Mask - Encounter 7 - change to encounter 13
Fearsome Mien - Encounter 7 - damage is psychic only, not psychic and thunder
Walking Earthquake - Encounter 7 - (save ends) to remove your ability to sustain the power
Scatter Like Stones - Daily 9 - Miss: Half damage & slide the target and each enemy adjacent to it 1 square
Burrowing Bolt - Daily 15 - Secondary attack is not reliant on primary
Caustic Blood - Daily 15 - Miss: Half damage, ongoing 5
Feast of Mojo - Utility 16 - Wild: Allies can spend a surge OR roll a save
Beneficent Whirlwind - Daily 19 - Attack: Cha vs. Fort; burst 3; Hit: 2d8; Miss: slide 1 only.
Madness Strike - Daily 19 - Miss: Slide Wis mod; Hit: Wait to slide until the end of the creature's turn, whether it moved or not.
The Rumbling Earth - Utility 22 - Minor Action
Stormwall - Utility 22 - Daily instead of encounter
Crushing Coils - Daily 25 - ongoing damage starts at 10; Miss: Half damage, ongoing 10
Curse of Rage - Encounter 27 - an encounter or solo enemy is dazed instead
Theft of Fire - Encounter 27 - Elements: Only a number of allies equal to the number of enemies hit may spend the healing surge
Born of Stone - Daily 29 - no penalties or rerolls on these saves can apply
Reflected Destruction - Daily 29 - works, but needs to be totally reworded
The Spine of the World - Daily 29 - targets appear on top of the wall?
~ fissionessence
EDIT: I just found out some terrible news . . . according to the PH2 rules for the Spirit power keyword, none of the witch doctor's powers can be used unless his spirit companion is present in the encounter. Since the witch doctor doesn't get a spirit companion, none of his powers can ever be used! Maybe you could errata the witch doctor's mask to say it counts as a spirit companion, but who knows what kind of awkward rules issues that could create
[/tongue in cheek]