Introduction
It was just announced that Arraetrikos, the preeminent DDO boss for nearly a year, has supposed to have been casting Greater Dispel Magic all along, even though it has never worked until a very recent surge of lag. This serves as a good reminder of the serious problems Dispel Magic has fitting into DDO gameplay.
First, it's important to understand the major changes to the underlying gameplay between D&D and DDO, and how this has shifted the power of buffs, debuffs, and dispels. Because DDO is a realtime game, there is no opportunity for the Dungeon Master to say "Ok, so you walk down the path for 2 more hours and then- roll for Spot check!". Time moves at a constant rate (except when you rest), so there's less chance for minute/level buffs to expire between encounters. Also because of the automatic dice rolling, more combat can be handled in a game session, meaning DDO PCs will face more monsters per minute than D&D characters would meet. That further magnifies the value of buffs on the PCs, because those buffs last for all the monsters in X unit of time, while offensive spells work only on the Y number of monsters attacking at one time.
The obvious conclusion: since PC buffs are more important, for an enemy to use Dispel Magic to unbuff is relatively more valuable than most any other spell they could cast. The converse is also true: for PCs to dispel enemies is unlikely to be helpful.
With that design consideration in mind, here are assorted changes to improve the Dispel Magic family of spells so it can be a better and more-balanced part of DDO gameplay, instead of dispelling and non-dispelling enemy casters being so completely different levels of threat. I don't think it's particularly important for DDO design focus to go on improving Dispel Magic gameplay, but if that were desired, here are some ways to do it.
Background notes:
Dispel Magic is level 3 and allows a maximum caster level modifier of +10.
Greater Dispel Magic is level 6 (bard 5) and allows a caster level of +20.
Break Enchantment is level 5 (bard 4) and allows caster level +15, but is only supposed to work on harmful enchantments, transmutations, and curses. However, the DDO version can also remove lingering environmental spells.
Suggestions
1. Make Dispel Magic (and similar) a multiple-choice spell, using a popup window like Resist Energy. The four choices are:
a. Dispel All- like the current spell
b. Dispel Defensive- attempt to remove only harmful spells
c. Dispel Offensive- attempt to remove only beneficial spells (those that would be removed by a rest shrine, plus Fingalar buffs)
d. Dispel Smart- act as Offensive or Defensive, depending on if the target is a friend or foe.
Obviously, this change would lead every caster with Dispel to put Dispel Smart on their bar as the preferred mode.
2. When Dispel Magic (and similar) is cast without a selected target, it shouldn't apply to the caster. Instead it should work as an AOE dispel that removes lingering environmental spells from a circular AOE. If used in Smart or Defensive mode, it only removes hostile effects. In Offensive mode it removes friendly effects. In All mode it gets both.
3. For reasons of D&D fidelity only, remove the ability of Break Enchantment to clear lingering evocations, conjurations, and the like, as they can now be handled by untargetted Dispel.
4. Add Gust of Wind as a wiz2 spell which acts as Dispel Smart, but only against cloud-based spells like Obscuring Mist or Glitterdust. In addition, it could have a weak CC knockdown against Small enemies.
5. Make the central eye beam of a beholder suppress magic for 3 second intervals, instead of dispelling it. (Beholders should not act like they spam CL 500 Dispels every 3 sec, as that is far above their supposed challenge-level)
6. Add Suppress Magic as a new level 2 spell, for any class that gets Dispel Magic. It functions similar to Dispel Magic (including the multiple-choice menu described above), except that instead of being truly removed, spells it hits are only deactivated for 6 sec + 1/level. (It can be Extended). However, the caster of Supress Magic gets a +2 bonus on the caster level check.
7. Add Greater Suppress Magic as a new level 5 spell, for any class that gets Greater Dispel Magic. It functions as above, except with the obviously higher caster level limit.
8. Change the majority of monsters who cast Dispel Magic or Greater Dispel Magic to use Supress or Greater Supress instead. From the players' point of view this is a weaker attack, because their buffs return in under a minute. However, from the monsters' selfish point of view it's better, because the higher caster level makes it more likely to success than Dispel, and they won't care what happens when it expires because their fight is over by then. (Monsters do not generally look ahead to the future after they're killed, so their tactics don't put value on weakening the players for their buddies to kill later)
9. New enhancement: Tenacious Magic I, II, III. Available to all casters, you gain a +1,+2,+3 bonus on rolls to resist Dispel and Suppress.
10. New enhancement: Counterspell Mastery I, II, III. Available to any class that gets Dispel Magic, you gain a +1,+2,+3 on Dispel/Suppress Magic rolls.
11. Altered feat: Spell Focus Abjuration also gives a +1 bonus on dispel checks, and so do Abjuration Focus magic items. (Arcane Focus items don't have this benefit)
12. New enhancement: Spellcarved Soldier I, II, III. Available to Warforged, beneficial spells on you have +1,+2,+3 bonuses to resist Dispel and Supress attempts. (Based on material in Races of Eberron. Note that the Spellcarved Prestige class could be expanded into a whole racial class specialty)
13. New magic item properties like Resilient Magic, which grant beneficial spells on the wearer a +X bonus to resist Dispel/Suppress attempts.
14. Alter enhancement: Arcane Archer so that the character gains a +3 bonus to caster level for the purpose of dispel and SR checks against the targets you damage with an arrow, lasting for 8 seconds.
15. Add Greater Dispel to the Paladin list at level 4. This is to correct a simple oversight: D&D paladins have caster level = level/2, while DDO paladins have double that. Therefore D&D pallies improve dispelling at every 2 levels, and are always far behind wizards. But DDO pallies are exactly equal to wizards up to level 10, and then stop improving because they hit the cap for non-Greater dispel. Since their caster level is higher, they should be able to use it for Greater Dispel. (Alternatively they could be given a 50% CL penalty when using Dispel Magic, but I wouldn't suggest that). (Paladins, then, would have Greater Suppress at level 3)