Wish is a conjuration spell that is able to be used to duplicate lower level spells as follows:
The basic use of this spell is to duplicate any other spell of 8th level or lower. You don't need to meet any requirements in that spell, including costly components. The spell simply takes effect.
When used in this way, does the resulting spell count as a conjuration spell or whatever the school duplicated spell is?
As an example (since there was some confusion): say I used wish to cast geas on a creature. After a period of time passes I cast detect magic on the creature. What school of magic do I detect?
Best Answer
The spell's school is whatever the duplicated spell's school normally is
Duplicate here mean to "make or be an exact copy of". Note that the wording says the entire spell is duplicated, not just its effects. An exact copy of a spell means that it is identical in every aspect, which includes school.
If wish was intended to only take some of the characteristics of the spell and not others it would say so. In fact, it does say so, but only for two specific things.
Wish specifically indicates things that are not duplicated from the spell
Wish tells us that only one thing is different casting a spell using wish versus casting it normally: requirements of the spell do not need to be met.
Also, it is implied by the wording "the spell simply takes effect" that wish also overrides the casting time of the duplicated spell.
Since no other exceptions are noted the spell should be treated exactly as if the spell had been cast normally including duration, range, school, etc.
Wish only lasts for an instant
Wish is an instantaneous spell which means no matter what it is gone the instant after you cast it. But say you used wish to cast a spell, say geas, on a creature using wish. The instant after wish is cast the only effects remaining are going to be of the spell it is duplicating not wish itself.
Wish conjures a duplicate of another spell
Essentially, it seems that using wish to duplicate another spell would result in the casting of a conjuration spell with an instantaneous duration which then results in another spell taking effect with all the details that that spell has (including school). Wish conjures the other spell into existence and then disappears leaving only the conjured spell's effects.