Midian Realms Forum

Orbs from outside an antimagic field penetrate an antimagic field
The description of the 6th-level Sor/Wiz spell antimagic field [abjur] (Player's Handbook 200), in part, says, "The effects of instantaneous conjurations, such as create water, are not affected by an antimagic field because the conjuration itself is no longer in effect, only its result."

The 4th-level Sor/Wiz spell orb of acid [conj] (Spell Compendium 150) et al. are all both spells of the conjuration subschool creation and spells that possess a duration of instantaneous. This means the orb spells neatly and completely meet the requirements for remaining unaffected by the spell antimagic field.

Thus, no matter how stupid it may seem, when a wizard casts the spell antimagic field, an enemy sorcerer outside the field can cast the 4th-level Sor/Wiz spell orb of force [conj] (SpC 151) and send that instantaneous effect of the creation subschool zipping right through the antimagic field effect without a problem to—potentially—bonk that wizard right on the noggin.

There's no way for me to justify this except to say that no matter how extraordinarily convoluted, contradictory, and controversial the effects of antimagic are generally, this is one of the areas that the rules surrounding antimagic are actually clear on: The orb spell effects really do go right through an antimagic field effect and can, with a successful ranged touch attack roll, deal their damage normally to a creature within.