[P3D]

You don't need Khysts to get curse.
There's that lvl 0 summoned hag for 2 death gem which has a Curse special attack.

More anti-SC stuff
There's also an ethereal troop for a single air gem, which has Attack skill 21 with a Plague Scythe doing 19 damage. They are unfortunately fragile and you can only summon them one by one - and by D random starets only (A1D1).

The Zmey (fire dragon) summon is actually nice. Flying 45HP, 13prot, 3xbite+breath, for a mere 3 fire gems. Problem is being cold blooded comes with 10 Encumbrance in cold-3.