Defenses for a warlock's lair?

[Shpadoinkle]

So I've got an NPC I'm working on, a 16th level warlock, who's going to be important in some ways in a game I'm working on and I want to have her lair statted out, including stuff like traps and other intruder countermeasures.

So far I've got two things planned- first, half of her lair is underwater (not a problem for the warlock thanks to having the Swimming the Styx invocation.) Second is a trap that casts a Summon Monster spell (haven't settled on what level yet) placed at every entrance to the building, that summons monsters in another room, who then move to entrance that triggered the spell so that it's not immediately obvious that they're present as the result of a trap. The trap is a 5' x 5' panel set in the floor and triggered by actually stepping on it, so a four person party walking across it would trigger it four times. The main problem with this one is that it doesn't really work for the underwater half of the base and there's no easy way to bypass it (the warlock bypasses it in the above-water half by using Fell Flight.)

Any other thoughts or ideas for traps that wouldn't be horrendously expensive or troublesome to bypass once you know the secret, that are within the capability of a 16th level warlock to create?

[NevinPL]

Any other thoughts or ideas for traps that wouldn't be horrendously expensive or troublesome to bypass once you know the secret, that are within the capability of a 16th level warlock to create?
Hire a lot of mercenaries (Sahuagin would fit nicely in an evil, aquatic environment). Arms and Equipment Guide has info about it.
Some (aquatic) monsters (preferably somewhat intelligent, or trained) could work too. I think I saw some aquatic making template somewhere, but I doubt it's for 3E.

[Troacctid]

Don't use floor tiles; use proximity triggers. They can be bypassed with a code word, like with an alarm spell. Give the Warlock some Autohypnosis so he can easily memorize all the locations and their complex passwords.

Speaking of alarms, make sure there's an alarm to alert the Warlock of intruders.

And don't be afraid to bust WBL wide open; NPCs aren't bound by the same wealth guidelines as PCs. You can give the Warlock any magic defenses you can think of.

[Flickerdart]

And don't be afraid to bust WBL wide open; NPCs aren't bound by the same wealth guidelines as PCs. You can give the Warlock any magic defenses you can think of.
This is half-true - NPCs are bound by much tighter WBL guidelines. Though it's up to the DM to give them traps and allies on top of that, they would be separate encounters with their own XP and rewards.

One feat I like to give warlocks is Dark Speech, for obvious reasons. Using it to create hive minds out of swarms is really useful with various invocations, but the warlock could just keep a room full of bees or whatever and then drop Dark Speech on them whenever he needs to pass. It's fairly trivial to ignore the Constitution damage this incurs (since Warlocks will want to mitigate CON damage from Hellfire Blast anyway - are there Warlocks that don't take that PrC?). Since the hive mind's suggestion will last for 16 hours, the warlock can imbue it when he leaves for the day, and it will still be there when he comes back, and which point he can renew it.

This is kind of nasty, though - a typical bee colony contains 10,000-80,000 bees, which would give the resultant hive mind a ridiculous intellect and more powerful sorcery than any archmage in the world (as a level 186 sorcerer). Presuming that you want this to be an encounter less powerful than the warlock himself, aim for CR15 and work backwards. The hivemind CRs are super-wonky for small and weak base creatures like bees, so let's just say that 15th level Sorcerer casting is what we want. This means we need to hit 32 Charisma, or +26 Charisma after the 6 Charisma established by having 150 bees. At 50 bees per point of Charisma, that gives us 1300 more bees, or 1450 bees in total.

[NevinPL]

This is half-true - NPCs are bound by much tighter WBL guidelines.
Yep, never really understood that (yeah, I know "Heroic Fantasy", but what's heroic about beating a rusted sword wielding marauder, with your "Widow, and orphan maker +5" ?). As the other "differentiations" between PC's, and NPC's.

I'm planning a Warlock as a future BBEG too. But I plan him to be a "evil scientist" - pseudonatural creatures (LoM), grafted humans, monsters (FF, LM, LoM, SK), mutants (Dragon 350), etc.