If you can only pull from two classes for additional abilities... Lancer and Archer seem to be where it's at... combining their abilities gives you 40% extra damage (Blood for Blood and Raging strikes, respectively ((if they stack)), on a three minute cool down and an emnity mitigation ability (Quelling strikes) that will prevent the 25% extra damage taken from "Blood for Blood" from making you a drooling puddle of arcane punching bag.