ISBoxer: Multi-Mode FTL Targeting.

[ZorbaTheGeek]

There may be a better way but I would try:

Create an interrupt-cast keymap

Actions
  Step 1
    Target group shaman => /Cast wind shear
    Target group Mages => /cast counterspell

Make a round robin keymap for Interrupt-Mob with a bound hotkey

Step 1
   Action do "interrupt-cast" keymap => Target slot 1
Step 2
  Action do "interrupt-cast" keymap => Target slot 2
etc

It's untested (It's late and my brain is telling me this will work) but it should mean you never have to change the "Interrupt-mob" keymap, this is the one you actually jab to stop a spell cast. Instead you just add class specific actions to the "Interrupt Cast". The intention is that "Interrupt-cast" targets by class, but you've already specified a specific character slot by the round robin action of the calling keymap.

EDIT: Let me know if it works, I've not got time to try this one out tonight. It's quite possible that the Interrupt-cast keymap wont be restricted to the slot and all of a class will still cast.