http://wiki.bluegartr.com/bg/Lunge
Code
Damage = ( Main-hand weapon Skill × (0.5 + Number of Runes × 0.25) ) × Number of Runes × Magic Multiplier Terms
Skill * 1.25 * 3.0 * MAB/MDB
Skill forms the base damage with the runes acting as a multiplier and the final value appears to follow MAB/MDB rules. There isn't any dSTAT term nor any other stat that effects it. Also it's subject to resists like other magic abilities are.
So what sets would be the best for damage then? Lots of MAB for sure.