Whoo, thanks for the pointers.
Did what you said, put Shima in front of Onghro as he was the strongest, equiped every scroll, potion and bandage that I had to one of the the 3 PCs Quick Use slots.
Myself and Nathalie used one of our extra abilities and set about teh guy summoning imps up while Shima took a shoot at Onghro each turn, once the stooge was dead myself and Shima with the aid of the scolls and potions where able to beat the crap out of Onghro while Nathalie took care of everything else as she was strong enough to whipe out one Ipm, Wretch or Wolf on each turn.
Job done, I must start giving more credit to magic in these type of games