It's not a lot of damage, but a level four summon monster can get you a lantern archon with two 1d6 light ray touch attacks/round. The light ray is an extraordinary (=nonmagical) ability, and will go through the antimagic.
(This works better if you have time to prepare and higher level spells, so you can summon a small army of lantern archons.)
(This works better if you have time to prepare and higher level spells, so you can summon a small army of lantern archons.)