I'm not exactly sure if this would work or not so wanted to throw it out there and see what you all think. What about a lone slann with ethereal and afew other abilities(maybe magic resistance and free dice) plus lore of death with the steal soul spell. Then taking the slann and ramming it into the flank of a charecter's unit effectively tieing up the unit and putting you in an excellent position to steal the enemies soul. or not neccasarily that idea but something similar in regards to a ethereal "combat slann"
There was a discussion about this in Tactics recently: http://lustria-online.com/viewtopic.php?f=15&t=2813 Hope that helps.
The "combat slann" isnt really discussed in the linked topic. The anchor slann is only a gimmic unit, something for fun / shock value. First of all you got to make him a BSB with Warbanner, this way he has static 2 CR. Against most enemys this means he looses by 3 every round, so he has a rerollable LD6 to rely on, hardly very useful. Against heavy hitter however, like knights with little SCR, monsters (this guy is a Hydra killer =P) and elite units that relys on ACR. He costs 350+ pts tho, and if you are up against a deamon army he is 100% useless.