pogre said:
Obviously, I need help with high level dirty tricks!
Sounds fun!

A few ideas...
Imprisonment Contingencies: What if this archmage was the former "defense against the dark arts" teacher who cast
imprisonment on several of the Mage University's worst enemies, trapping them on the university grounds? And what if he worked a "back door" causing the imprisonment spells to be broken one-at-a-time under specific conditions? What if he'd "broken the code" allowing for the casting of multiple
contingency spells on himself? You could have unique
contingencies worded thus, for example:
"When the
death ward affecting me is triggered or dispelled, the
imprisonment spell I cast upon Kabalth-Durim, the wastrilith bound to the university's fountain, will end."
"When my Fourth Glyph of Warding in the Western Wing's Stained Glass Gallery overlooking the flying buttress facing Dundamere is triggered or dispelled, I am protected by
mirror image and the
imprisonment spell I cast upon the death knight Revander, binding him to the very brick and mortar of the Grand Foyer, will end."
Thunder Gate Combo: This is a pretty fanatical / desperate move and assumes you don't already have a plan for the archmage's 9th level spell (e.g.
foresight)...
The archmage opens a
gate to a realm of unspeakable horrors right behind the PCs, and his apprentices (possibly using the Ready action) cast a whole bunch of
thunderwave spells (ideally after the PCs are peppered with
bane by an allied bard or cleric first) to force them through the gate. Now the PCs are faced with the choice of leaping through the gate but be pursued by the hordes of the Abyss (or wherever) or holding the line against the hordes of extraplanar monsters and trying to organize a withdrawal back to the Material Plane.
This becomes more complicated if the PCs have a hair-trigger NPC ally who is gunning for the archmage, and risks disrupting his concentration on the
gate, potentially stranding the PCs in the Abyss (or wherever).
The Final Lesson: Until this coup, the archmage was playing the part of a magic professor, right? You know all those spells with a "if you cast this spell every day (or every 7 days) for a year, it becomes permanent" clause? He's been planning for this. The coup begins with his final lesson demonstrating the
guards and wards spell. The spell becomes permanent! His co-conspirators are immune and/or know the password to evade the spell's effects, but everyone else is screwed. Personally, I like setting up the two
magic mouths from
guards and wards to trigger otherwise obviously avoidable
glyphs of wardings, casting
thunderwave along a narrow hall lined with stained glass overlooking a precipitous fall, showering the PCs with glass shards and defenestrating one or more... a PC can cast
shield or
feather fall, but not both. YMMV.
Pairing the heavily obscured foggy corridors (created by the
guards and wards) with several
invisible stalkers seeking out specific high-value targets would be thematically apropos.
The main enemy is a mage who has engineered a coup in the Mages' University and is working to take over the realm itself. He has access to a couple of apprentices. The problem is a 20th level mage even with a shield guardian are going to be a speed bump for this group - Even if I add in a couple of high level apprentices. I would like to make the epic challenge, well, epic.
Please give me suggestions.
What allies should the rebel mage have? Where do the PCs need to confront him?
This is not a 'gotcha' encounter - I just want it to be interesting and tense.
Thanks for helping me!
To orchestrate a successful coup, the archmage is going to need more than "a couple of apprentices." He needs sympathetic allies in as many sectors of society as he can get – civil administrators / bureaucrats, at least one branch of the military, temples or religious figureheads, etc.
I'd say if he doesn't have a 1/3rd to a 1/2 of the mages in the Mages' University backing his coup, then he needs to be drawing on outside assistance from his allies in the military, temples, government, etc.
My point being: This isn't a smash-and-grab job. The point at which the archmage is taking violent action against the ruling council in the Mages' University indicates that he's confident enough in his support base to
hold power after the violent coup.
That's really important to consider.
You folks who have designed high level encounters and adventures more than me - is there a way I could leave a clue that the bad guy, once vanquished, has a hidden clone?
The spell reads:
Sort of the PCs trying to restore the mage for some bizarre reason, how can I leave a clue that this has happened?
- A scar on the dead archmage's left inner arm where 1 cubic inch of flesh was stripped away in order to cast the clone spell.
- Several spell components from a particular seaside town known for its pristine saltwater "healing" pools. Hinting at archmage's purchase of saltwater for the clone spell.
- In the aftermath, his apprentices sneak in to cast raise dead on the corpse, but... it doesn't work. Maybe the PCs are called in when the apprentices seal themselves in the archmage's tomb, and while confronting them, the apprentices (and the PCs) realize the resurrection isn't working. Figuring out why could lead to investigation... scar on inner arm... archmage recently commissioned a dwarven craftsman to make an expensive jeweled man-sized urn... his favorite staff was no longer tipped with a diamond... Arcana/Investigation checks and/or divination to put the pieces together.