One, there is no such thing as an “antimagic barrier” – antimagic field does not block line of effect, it only suppresses magic inside of it. All magic can pass through an antimagic field to the opposite side of the field.1
The argument is that the effect of instantaneous Conjuration/Metacreativity (creation) spells/powers can exist inside the antimagic field. This is very well-supported by the rules, and rather difficult to argue against:
An antimagic field suppresses any spell or magical effect used within, brought into, or cast into the area, but does not dispel it. Time spent within an antimagic field counts against the suppressed spell’s duration.
The spell has no effect on golems and other constructs that are imbued with magic during their creation process and are thereafter self-supporting
Elementals, corporeal undead, and outsiders are likewise unaffected unless summoned.
If the spell has an instantaneous duration, the created object or creature is merely assembled through magic. It lasts indefinitely and does not depend on magic for its existence.
If the power has an instantaneous duration, the created object or creature is merely assembled through psionics. It lasts indefinitely and does not depend on psionics for its existence.
While neither antimagic field nor Conjuration/Metacreativity (creation) specifically calls out the other, the effect of antimagic field does not, to begin with, have anything to do with instantaneous Conjuration/Metacreativity (creation) effects, as the latter do not rely on magic for existence. Suppressing magic therefore does nothing to them, and they are not magical effects that would be suppressed. Furthermore, parallelism with the specific explanations of constructs and the undead indicates that this kind of distinction was very much intentional.
Yes, instantaneous Conjuration/Metacreativity (creation) effects can exist inside antimagic field
This still does not allow Conjuration/Metacreativity (creation) spells/powers to be cast/manifested inside the field, nor for the effect to be directly created inside the field; it only allows the effect, once created, to safely enter the field (e.g. when launched from outside as part of the spell, as with acid splash).
Whether or not there is transparency between magic and psionics has no effect on this ruling; if not transparent, antimagic field would not affect any psionic powers, and thus would still not affect Metacreativity (creation) powers.
- Yes, antimagic field itself mentions a barrier that encloses the field. Personally, I find this to be a relatively-problematic way to think of the spell, but it is what the spell says. My point here is not to dispute that, only to clarify about a common misconception about shooting through an antimagic field.