The rules for counterspelling are pretty clear
Counterspells
It is possible to cast any spell as a counterspell. By doing so, you are using the spell's energy to disrupt the casting of the same spell by another character. Counterspelling works even if one spell is divine and the other arcane.
But where are the rules for dispells? Can you dispel An enlarge person thats already in effect with a reduce person, or does both spells being active on the same creature simply result in a net 0 effect until one or the other wears off?
Read the spell description of enlarge person and reduce person and haste and slow. Otherwise use dispel magic.
I have, many times thank you. It doesn't answer the question.
Underneath combining spell effects it says spells with opposite effects will negate or counterspell certain spells assuming it makes specific mention of such in the spell. So I think the end result is 0. My core rulebook says pg 209.
Some spells negate or counter each other. This is a special effect that is noted in a spell's description.
Counter spelling has a section that's laid out. There doesn't seem to be one for negating.
If someone has an enlarge person cast on them that runs for 4 minutes. They are then a target of a reduce person that would normally last 8 minutes.
1) Do they get the save vs the reduce person or is the reduce person acting as a dispel magic?
2) If affected by the reduce person are they normal for the remaining 4 minutes and then shrunk for 4 minutes or do the spells cancel each other out completely.
-Mostly I'm bringing this up because someone mentioned using Daylight as a dispel magic for a deeper darkness spell... but the two spells don't seem to interact like that.
The rules for counterspelling are pretty clearCounterspells
It is possible to cast any spell as a counterspell. By doing so, you are using the spell's energy to disrupt the casting of the same spell by another character. Counterspelling works even if one spell is divine and the other arcane.
No, the counterspell action requires you to either use a specific spell (the spell that you are attempting to counterspell), a spell that is specifically stated as being able to counterspell another (spells stating they can be used to counter X spell; typically a spell with a contrary effect) or the spell Dispel Magic (when applicable).
But where are the rules for dispells? Can you dispel An enlarge person thats already in effect with a reduce person, or does both spells being active on the same creature simply result in a net 0 effect until one or the other wears off?
PFRPG pg. 272
As for the difference, the spell states it dispels so I would use the dispel mechanic. Also, the only time something can be "dispelled" is when it is already in effect.
Think of it this way. If you are readying an action to counter a spell and it is Enlarge Person, you could use Enlarge Person, Dispel Magic or Reduce Person.
If the spell Enlarge Person spell is already in effect on a target and you cast Reduce Person, the Enlarge person's effect is treated as if it is under a "targeted dispel" versus a specific effect (Dispel Magic spell description).
The difference: A dispel mechanic doesn't rely on a save, it is a caster level check. A dispel mechanic also ENDS the effect, not subdue the effect for a duration.
If you wanted to use it as a net effect of 0, you'd have to cast the spell, hope the target doesn't make the save (to be effected by Reduce) and doesn't have SR (which is not an issue with the Dispel effect) from what I'm reading (well skimming). I would also posit that they would word it differently, as they have spelled out times when effects would overlap but not dispel each other.
Underneath combining spell effects it says spells with opposite effects will negate or counterspell certain spells assuming it makes specific mention of such in the spell. So I think the end result is 0. My core rulebook says pg 209.Some spells negate or counter each other. This is a special effect that is noted in a spell's description.
Counter spelling has a section that's laid out. There doesn't seem to be one for negating.
If someone has an enlarge person cast on them that runs for 4 minutes. They are then a target of a reduce person that would normally last 8 minutes.
1) Do they get the save vs the reduce person or is the reduce person acting as a dispel magic?
2) If affected by the reduce person are they normal for the remaining 4 minutes and then shrunk for 4 minutes or do the spells cancel each other out completely.
Reduce person says it can counter (not possible as Enlarge has already been cast and is in effect) or dispel. There doesn't seem to be a choice in the matter as per the spells language. If you cast Reduce Person on a creature with Enlarge Person, the Reduce person spell attempts to dispel the first effect. Again, this is not a net effect of 0 as the spell is removed/ended, not "subdued" for 4 rounds and then reduce person takes effect.
-Mostly I'm bringing this up because someone mentioned using Daylight as a dispel magic for a deeper darkness spell... but the two spells don't seem to interact like that.
These spells can be more interesting as they can have a mobile focal point (target the spell is cast on) and so can have overlapping fields of effect. Given the spells and the rules, if both of these spell effects are moved together and then overlap, the area of overlap is a net effect of 0. Neither of the spells "targets" are being influenced but the spell effects are being brought to bare on each other and in this area neither spell works as they are countering each other as they are equivalent strength. This would continue on until one effect or the other expired (duration ends for example) at which point the remaining spell effect would become prominent.
Now if someone was casting Daylight on the target of the Deeper Darkness or someone was attempting to cast Daylight specifically to remove the Deeper Darkness, the dispel mechanic would be brought into the equation per the spell description. At this point we are getting into the "targeting a specific effect" again.