Warlocks basically get half level d6 damage. Evocation spells by spell level 3+ are doing CL d6 damage or better, generally. How do you have nothing close to that?
He was doing two blasts every round which are touch attacks if he hits with both that is 10D6 in damage. The DM also made a feat for him where he can absorb spells he takes damage but he can channel the damage into extra hit dice of damage so he was often doing upwards of 15D6 at eighth level.