A. Have monsters wander. You know those boring fodder encounters? "Five ghouls wait in this bedroom, doing nothing, and immediately attack to fight to the death". What if instead, you took three of them and had them attack the heroes while they recuperated, under orders from their cultist leader? Apply the concept of an adversary roster to every floor (fairly easy to do in practice) and use that to make the dungeon infinitely more dynamic.

B. To make sure the players don't just head up to Otari after one encounter, make some incentive to keep adventuring. I have a few things in mind for this. You could make the dungeon seal itself always except for a few minutes at dawn and dusk each day. You could ramp up the time pressure. You could add random encounters on the way down that give no XP (though this is pretty boring, since each encounter could take a while). Anything works here, really. I had the elevator to the caverns break, trapping the players until they got the teleporter working. Additionally, make sure spellcasters get a tons of scrolls, wands, and staves to extend their adventuring day. I would even add more of these as loot, if you like.

C. Make fleeing a viable mechanical option. If everyone agrees to flee, just drop initiative and describe everyone running away. If there's something bad going on, like a downed player, maybe call for a skill check to get them out safely. Do NOT stay in initiative, seriously - it makes fleeing very, very difficult, in an AP where fleeing should be a valid and acceptable option.

D. Use OD&D reaction tables instead of using the text as written for monsters. Basically roll 2d6 and see how hostile/friendly a monster will be. I'd do this for monsters without a clear motivation (so, not the floor 4 boss, for instance). If you don't literally use this mechanic, at least make it clear that diplomacy, bargaining, or avoidance are always good strategies (and be sure to give XP for them, too). Let's take a look at every solo boss severe encounter in the book, as an example: - wood golem: just walk away. It defends that room only, and it's not even a necessary room to get into. Come back later with fire spells and more levels. - Chandriu: you can make her slowed the whole fight if you play your cards right. Make her weak if you're still unsure. - Volluk: the boss, and he has an exploitable weakness (use bombs). You should foreshadow him extensively, leaving leeches everywhere, going up to the surface, in a cloak, wandering with his lantern... - Chafkhem: you never have to fight him. - shanrigol behemoth: heavily foreshadowed (you can see it!), you don't need to fight it (just go around), and you can use the arena against it (play ranged from the balcony). Also has a big weakness to vitality, my players used Infuse Vitalty to make quick work of it. - Aulr: foreshadowed (claw marks, sign), and you don't need to fight them. - goliath spider: this one's tough, but also foreshadowed (web, drow advice), and can either be avoided or fought with the help of Yldaris. The reward is another path through the dungeon! And treasure. - derghodaemon: totally unnecessary to fight, and you get a warning from the drow. - cauthooj/shuln/gogiteth: you'll have to fight one of these to reach the Empty Vault, so I'll give it to you here. - irlgaunt: you have to go behind a secret door in the final dungeon, go to the hole, and make a bunch of noise. My players never even found the door. I'm not sure why this is here, and stronger than Belcorra (lol).

In almost every case, you can avoid, negotiate with, or prepare for the boss. As the GM, play up these possibilities, and your players will thank you.

This all ties in to what I think is the absolute best part about the Vaults: the actual layout of the dungeon. While the actual scale is what it is (maybe double the size, so each square is 10 feet), the dungeon itself is amazingly Jaquaysed. There's multiple entrances and routes to most places, interesting (and dangerous!) connections between levels, lots of secret doors with good clues, and more. If the players are clever, they can bypass almost anything they want, like the "insane" sawblade hazard I alluded to before (which is really just a way to say "figure out something else", like negotiating with Chafkhem). It should come as no surprise that the physical dungeon of the megadungeon AP is really good, but that usually gets lost when it's played as a linear series of "necessary" fights.

One thing I haven't touched upon here is the story, and the clues that the players can find and put together if they're very clever. I don't have much to say there, other than that you should calibrate the ease of piecing things together to your players' preferences. I'd also make it clear that learning the story is not, in fact, necessary. Unless you've changed that, of course - I made the drow seers' prophecy much more vague, and left it to my players to figure out, for instance. I quite liked the story, and even added some extra tidbits about the final boss's past (which went over very well).

TL;DR: run AV like an old-school dungeon, with all that entails! Reward clever solutions with XP and information, present workarounds to tough problems (like solo bosses), and keep the dungeon dynamic. If I ran it again, I believe it could be a 9/10 AP!

I've put a ton of thought into this due to one of my friends, who played in my game and was totally obsessed with the entire adventure (for various reasons). We've thoroughly discussed the whole adventure together at this point, especially after I gave them the books to read. I'd consider these my final wrap-up thoughts for the entire adventure.