feel free to post anything you'd love to see in a heretic-like game. 
my vote: other
the body switch spell. switch your body with any other actor inside the game. become a dog. become a magic artillery having 2k hitpoints. throw all weapons away, switch your body with the boss and kill your weak human one.
The rope bow in Dark Messiah was awesome, but grappling hook if far superior…especially if you can re-grapple in mid-air.
that's what "like spiderman" means
it would even be able to attach the hook to some flying projectile/enemy and let it carry you. and now imagine:
- a flying boss
- you, having grappling hook
- lava below yourself
you have to stay in air using the hook on the boss while using other weapons and spells to kill the boss. the possibilities are infinite.
If well implemented, the cloning spell could be just amazing… imagine creating a wall out of nothing to block your enemies!, no funds? no prob! clone treasure!, Clone yourself as a decoy! 
Or clone the monster and hope it attacks the original before it realizes you're there.
Being a die hard Zelda fan, I had to choose the grappling hook. XD
you could also clone the ultra hyper mega nuke you've just fired. i'm aiming for maximum flexibility for each one of the options.
the respawn spell for example could be used to get to an otherwise unreachable place by casting the spell and then comitting suicide. this calls for hard puzzles.
A spell to remove clothes from all NPCs.
To remove their armor/defense, of course!
A spell to remove clothes
It would limit the audience quite significantly if the rating is AO..
we do not have the resources to make a naked model/skin of everything. also, we already use some models that cannot be nakified any further (e.g. gargoyle). suggestion rejected.
You could strip Gargoyles from their wings or stone skin!
i planned to ignore all your votes and do the grappling hook anyway. }:-@
you have avoided the ultimate spell of course
not implementing the chicken spell is out of question, thus there was no vote for or against it.