Does dispelling with an opposing spell require a check or save?

Question

In Pathfinder there are a few spells that are effectively polar opposites, and as such have the text counters and dispells [opposite]. The rules for counter spell are spelled out fairly well, but I'm not sure about the dispelling. If I use a opposed spell that would normally allow a saving throw and spell resistance to dispell it's opposite, does that require a spell penetration check, allow a saving throw, or simply happen?

For example, the party is fighting a Wizard with Slow on his list. The party casts Haste. The next round the Wizard casts Slow on the party to dispell Haste. What rolls if any, are required for the dispell to be successful.

Answer 1

Tim Shadow replied to my e-mail with a third interpretation:

First I am happy help but not sure how "official" the answer is and two a GM could interpret the answer differently.

Going with your example at the end with the Wizard. So the party has Haste and the Wizard casts Slow on the party so each PC has to make a Save vs the Slow. If they fail the save they the Slow removes/dispels the haste with no other effect. If the player makes his save he is not affected by Slow and there for gets to keep his Haste spell.

Basically it works this way as your not actually affected by Slow until you have failed your Save. Or if you had Spell Resistance Slow would have to overcome the SR and then fail your save before it would remove the Haste.

Hope that helps.

Answer 2

In your case, Slow dispels Haste when the wizard casts it. No check is required.

Normally, only certain spells, like dispel magic can be used to get rid of an effect after casting. If you ready an action to counterspell, you can automatically cancel an enemy spell, with no check required, by using your readied action, and expending the same spell as the one being cast (or another same-or-higher-level spell of the same school, with the Improved Counterspelling feat). When counterspelling this way, a Spellcraft (DC 15+spell level) is first required to identify the spell being cast. Dispel magic and similar spells can also be used to counterspell, requiring a caster level check as listed in the spell's description.

Some spells have a specific notation in their descriptions that an opposite spell counters and dispels it. In those specific cases, the opposite spell can be used after the fact, and no check is required. Casting the opposite spell will negate the effect of the original.

Ex:

Darkness can be used to counter or dispel any light spell of equal or lower level.

(PF264; emphasis mine).

Edit: Updated the counterspelling description to mention the Spellcraft check, etc.

Answer 3

In general, you can't dispel with an opposing spell. The opposing spell is only relevant if you are counterspelling, which negates the target spell as it is being cast.

You can dispel an already-cast, active spell by using the targeted dispel form of dispel magic, which requires a dispel check.

However, slow specifically states that it counters and dispels haste. Treat it as a multiple targeted (as per slow), targeted form of dispel magic. Possible rolls would be: Spell resistance of each of the slow's targets, then a single dispel check (1d20 + the wizard's caster level) versus the DC of the haste (11 + the caster's spell level).