Its a Pull barb for maxium exp buff. You actually use both Cain's sets (lvl 23 and 70) and get both bonuses. The 30% additional exp bonus of the lvl 23 Cain's set are in addition to the 50% of the lvl 70 set. That's a nice addition in speed experience runs. You loose some thoughness but for speed runs at 60-65 that is ok with good heal monk.