In CBM, farstrike works pretty well against lesser or normal horrors, assuming you've got bodyguards that can stick it out for 2 or 3 turns at least.
I've made some minor death stuff and not gotten killed, just by scripting raise skeletons. They eventually overwhelm a lesser horror.
I always think I'm missing something if I've got an empty slot on a thug/SC
. Got regen, luck, reinvig? Add some MR, or attack or resistances. Tough to craft some items with AC up though.
Attack rear is iffy. You might get there, you might not. There's a morale check involved. More units == less chance to get by.