MaxKaladin said:
As far as taking the city, its true that Waterdeep has formidable defenses. At the same time all the enemy really needs is a good trick up its sleeve and you might just overcome all that. My favorite thought is if you could somehow generate a large anti-magic field.
Emphasis on "
somehow". This sort of thing would be a snap in some other games (Hero System leaps to mind) but D&D spells always seem to have really small areas of effect. I think the invading army in question was described as being led by 6th-10th level spellcasters? Without access to epic spells, how
do you take a spell that normally has a 10' radius, and make it cover an entire city?
And if we're just talking generally here, not about this specific campaign scenario but just about what would be involved in sacking Waterdeep: if you have access to epic spells, do you in fact need an invading army? Consider:
Dire Winter
Casting Time: 1 minute
Range: 1000'
Area: 1000' radius emanation
Duration: 20 hours
Saving Throw: None
Spell does 2d6 cold damage per ROUND to all creatures in the area not magically protected or otherwise resistant to cold; also creates a blizzard effect in the area.
(Better yet, summon a Xixecal, a Colossal Outsider(Cold) to attack the city. It has...oh, way too much going for it to list here, but it is an obscenely powerful 100+ foot high walking glacier with nine separate spell-like abilities usable at will, plus Haste and Meteor Swarm five times per day; it is usually accompanied by 2-5 adult white dragons and is continuously surrounded by the Dire Winter spell effect. Oddly, it's "only" CR 36.)
Pestilence
Casting Time: 10 minutes
Range: 0'
Area: 1000'radius hemisphere
Duration: Instantaneous
Saving Throw: Fort negates
Spell causes slow rotting death to plants, animals and people, drains CON, etc.
Waterdeep's spellcasters may well escape the effects of the Dire Winter or the Pestilence, but they'll likely be the only ones. Of course, if the goal is to eliminate
only the spellcasters and others with the capability to resist, and take over an intact city filled with cowed inhabitants, different spells would be indicated.