To expand upon what I was saying above...
When a caster from a specific realm learns a list, he learns to cast it from his realm. This is a given when a Channeling user learns a Mentalism list or a Essence use learns a Channeling list, etc. (based upon the option being used -- specifically Option 2.5 (full list availability) which also recommends Option 10.3 (ESF Mod of 20) be used).
When a character learns a list from another realm, and then casts spells from that list, he is casting the spell with his PP (which are of his original realm) and the spells are resisted against as being from the same realm. In other words, if a Cleric learns a Mentalist's base list, he casts the spell as a Channeling Spell and if a target has to resist, he resists it as if it were a channeling spell.
Thus when a character from RMC learns a spell list that might be considered Arcane, that spell list will be learned as and treated as if it were from a single realm (the realm of the caster). And that includes what can cancel or dispel it.
Now, if using the Archmage, from RMCI, or something similar. The Archmage would, in my opinion, be treated like a tri-realm hybrid since he can learn spells from all three realms and since RMC does NOT have a magical realm known as Arcane (the closest thing is the innate abilities of some creatures).
For his Base Lists, he would have to follow the same rules as for regular Hybrids, as stated on page 16 of RMC Spell Law. The Archmage would have to abide by the realm restrictions for all three realms when casting from his Base Lists. For his Open and Closed spell lists, he would have to abide the restrictions from the realm from which the list came.
In countering spells from a Hybrid, which we unfortunately did not cover in Spell Law, you have to counter the realm from which the spell comes from, in regards to the Open and Closed lists.
But this is more problematic when it comes to Base lists, since for the Hybrids and the Archmage, they are considered to be from all of the involved realms (2 for the hybrid, and 3 for the Archmage).
Now, if we make an analogy of a spell being like a house of cards - the shape of the house being what determines the spell, the number of cards being the level/complexity, and the different suits being the realm (yes, in this analogy, we only have 3 suits).
Then what happens when you do a cancel or dispel? You are essentially removing all of the cards of a given suit.
For a spell of a single realm, this removes all of the cards, and away goes the spell.
For a hybrid, it would remove half of the cards, and while there it a good chance that the spell will collapse, there is a chance that it will remain standing.
For an Archmage's spells (or arcane spells/abilities), you are removing about a third of the cards, and so the chance of the house falling is less than that of a hybrid spell, but it is still there.
Needless to say, we messed up in not covering this in Spell Law, in regards to the Hybrids, and in C&T because we didn't think it through well enough.
In C&T it says that only spells that affect all three realms can affect Arcane abilities.
I would have to say that it needs to be changed to the following:
Note: I am marking the following in green as a Potential/Provisional Ruling, until I can get more feedback from folks in this thread.
For Hybrid casters, it is already established that Open and Closed spells that they learn belong to the realm that they come from, when it is one of the two realms that the Hybrid belongs to.
Therefore, if a Hyrbid caster learns a list from the realm with which it is not associated (i.e. a Mystic learning a Channeling list), those lists are treated as Hybrid lists (i.e. of BOTH the Hybrid's realms).
This follows in the precedent of a caster from a single realm learning spell lists of other realms having those lists treated as being of the same realm as their Base Lists. If a spell user of a single realm learns an Arcane List, it would be treated in all ways, in regards to its realm and how it is resisted and/or canceled/dispelled, as if it were of that realm. If a hybrid spell user learned and Arcane List, then the list would be treated in all ways, in regards to its realm and how it is resisted and/or canceled/dispelled, as if it were another Hybrid list. In neither case, does this reflect what level that list may be learned to (that would be set by other options/rules).
Hybrid Spells -- If a spell list if of 2 realms, like the Hybrid Base Lists, then when a Cancel or Dispel against either of the Hyrbrid's realms is used, the defending spell must make a RR or be Canceled/Dispeled. However, it receives a +10 to any RR that it gets to make.
Arcane Abilities/Spells -- Being of all three realms, then when a Cancel or Dispel against any of the realms, the defending spell must make a RR or be Canceled/Dispeled. However, it receives a +25 to any RR that it gets to make. If an Arcane Spell or Ability is his by a Cancel/Dispel that affects 2 realms, then it's RR receives a +10. If it is hit by a Cancel/Dispel that affects all 3 realms, then it receives no modifier to its RR (note: this last replicates the existing C&T rule, so we aren't really changing the rule, but expanding it to cover what was previously missed)
