the only problem i found is that the ice bolts from the mercs forti can shatter the council when he kills them.
think the best 3 alternatives for that would be an eth corpsemourn (For the amp damage), ed/ias or max armor or just using wealth on the merc itself.
i also use an offencive nm merc for the best damage, since i made a 400/15 BotD ghostspear last night