Farcast:   Make it much more expensive, remove the ability to tie it to
something that moves (like a ship) and take away the Save Farcast State
spell.  Also, make Magical Shroud a lot tougher to dispel.
Aura Blast:  Allow an Absorb Aura Blast Amulet to be constructed, perhaps
using pretus bones or some such thing.  The amulet would be destroyed after
a certain number of uses, but then other characters besides necromancers
would be safe from the predations of necromancers.  An alternative would be
a protection from aura blast spell (or prayer?).
But it's not my game.
Rob