It's hard for me to test this with an enemy mob since dispel is such a rarity, so this may be superfluous.
Dispel 2 would only strip beneficial buffs and probably have a longish cool down. That gives potential/current encounters more variability and complexity when you or a group member has to be on the ball and ready to respell, especially when taking into account the time needed to switch out spell sets.

A use case I am imagining would be some sort of "raid" type encounter where you fight in a room with a mob you cannot attack along with the boss.

The way dispel is supposed to work...

If you are an enemy then dispel good spells first and then all other spells.
If you are a friend then dispel bad spells first and then all other spells.
Good or bad spells are selected in the order they were originally cast (sort of).

So a bad NPC should try to dispel your good spells first.

Note that an NPC with dispel is a very powerful enemy as it can strip you naked magically with devastating effects.
Builders use this feature with extreme caution.
I did have this in the initial RD2 but the testers complained enough that I removed it. No fun.

Is this what you are referring to?

Yeah sorry couldn't find an NPC to test this on, so this is superfluous liked I thought it might be.

I think anything that had dispel would have to be tuned with the expectation of lessened stats during the fight and the encounter being of a discrete nature. Tried a bit of rd2 the other day and the fact that some mobs can walk up on an on-going fight would make that dicey indeed.

How does the dispel order actually work? Like say I want to "save" my bless/prot/ms can I cast EW or even eat something silly like a mushroom first, then cast bless/etc to set that as the dispel order?

Dispel order: http://www.aranockonline.com/forum/viewtopic.php?t=1268

The dispel checks the spells in the order that they appear as icons at the top of your screen above your name. These are roughly in the order that you originally cast them but you can manipulate them if you really try. It will try to dispel good or bas spells first before going back and trying the rest.

So if you cast Light first (as it appears above your name) and a baddy tries to dispel you then it should dispel the Light spell first.

Maybe you should have left the Dispel in RD2.

Caramon can stand in UW pents and keep pounding completely unspelled. (With Shadow Helm and Champ axe equipped of course ) So More NPCs with dispel might encourage more use of high level Temps???

Do you do RD2 alot, Z? Solo? And using C2, B2 or poison alot in crowded corners?