thanks mark1 for the spinal kills save,but I still cant get it,I can only get 1 at that room then I try to do another one kill in later still no luck,that orc is stupid,he dont do spinal kill when enemies in low hp. damn it. I even using styx to hit enemies till low hp and die but orc is really no brain,frustated of this trophy.
EDIT

ONE,GOT ALL TROPHIES
hit 8 enemies at a time can be done early in where you fight oboth, make Orc to taunt and stynx to do the rain blades
poisoned daggers can be done at anywhere as long as 3 at the same time even one hit kill on them.