Buff Rite of Abjuration
I have pretty much _never_ used Rite of Abjuration, and I suspect most others haven't as well, or at least haven't on any kind of recurring basis. My suggestion to make it better:
Rite Of Abjuration - At-Will, Major
An arcane ritual disrupts an enemy's place in the Concordance.
Check Lore against the Will of an enemy within five squares. On a success, the target becomes Abjured and its focused, inspired and enraged positive conditions and buffs on it originating from an arcane ability are removed, dealing 3-6 Spirit damage for each positive condition and buff removed in this way. Undead, nightmares, magical and summoned creatures take 4-8 Spirit damage that ignores resistance and immunity.
Level 1 Lore
In this way RoA becomes actually worth using whenever enemy buffs and a certain subset of enemies are involved.
Vs Undead, Nightmares and Summoned creatures: Disrupting the magic that comprises an enemy or binds them to the world deals damage.
Vs Buffs/Emotional Conditions: Disrupting a target's Concordance ends their altered mental state, destroys their enchantments and results in proportionate psychic and spiritual feedback.
Also haven't ever used RoA except to test it out, or when I had an extra turn as enemies moved within range of other attacks. Either making it a minor action, or have it be an upgradable skill to something that does damage as Surrealistik suggested, would make it a lot more useful. Right now, it just (annoyingly) takes up space on my skill bar.
Rite of Abjuration as is is borderline useless; to say it 'isn't very powerful' is euphemistic to the point of being dishonest. Also, I'm not sure how my suggestion doesn't fit the flavour. I could certainly see reducing the damage on the disenchant, and omitting removal of the other 'emotion' based buffs, but beyond that, the recommendation is spot on.
I could live with making it a minor. Your suggestions for buffing it as a major are far too weak; I'd never use it versus a Gout of Flame/other attack unless the encounter was nothing but casters (with regards to the multiattack version), and even then it would require serious consideration.
As a debuffer, it'd still be trash as a Major. What would 'abjured' terrain spaces be?
I think that while Rite of Abjuration isn't very powerful, this suggestion doesn't fit the flavor of what Rite of Abjuration does, and is also potentially overpowered in terms of the damage it could do. Instead, I would suggest making it a minor action, or having it remove buffs (but not also deal escalating damage based on the buffs removed), or having it hit multiple targets/create "abjured' terrain spaces.