A Guide to Dungeons from a survivor of the Tomb of Horrors

Stormcrow Posts: 458 Mover and Shaker
Now that I've picked up Ellywick and Dungeon Master, I've got a few decks that blaze through dungeons at outrageous speeds, often clearing an entire dungeon and part of another one in a single turn. That's a lot of prompts asking which path to take through the dungeon! As a result I've developed a pretty good sense for which dungeons to explore and which path to choose when. Here I offer a basic overview, so you don't have to spend so much time reading the supports:

The Lost Mine of Phandelver

4 Ventures to complete. This is a low-level dungeon. Goblins and stuff. Very minor effects on gameplay, nothing harmful but also nothing too amazingly helpful. I recommend doing this one first, as it'll get you Dungeon Spoils fairly quickly with no ill effects.

Choice One: Goblin Lair or Mine Tunnels
Goblin lair is 2 goblin tokens, and the option to pick Storeroom next. There's nothing wrong with Goblin Tokens but a serious dungeoneering deck probably wants creatures that venture in the dungeon, which goblin tokens do not. Mine Tunnels is a gold token, and the option to pick Fungi Cavern next.
Verdict: Unless you desperately need creatures on the board, pick Mine Tunnels.

Choice Two: Dark Pool (always) and one of Storeroom (if you picked Goblin Lair) or Fungi Cavern (if you picked Mine Tunnels).
Dark Pool is gain 3 life, deal 3 to your opponent, which is always going to be fine if uninteresting. Storeroom gives your first creature +2/+2 permanently, which would be the best option if it didn't require going for the goblin tokens earlier. Fungi Caverns gives target enemy creature -6/-0 for one turn, which is fine I guess.
Verdict: Doesn't really matter much; Storeroom is usually best if available, Fungi Caverns can be useful if you need to temporarily nerf an opposing threat, but Dark Pool will always be basically fine and you don't have to think about it.

At the end of the mine you get to draw one free card that gets full mana. Not a bad gig, this adventuring stuff!

Dungeon of the Mad Mage

7 Ventures to complete. This is a higher-level dungeon but nothing that your adventuring party can't handle. It's the longest dungeon, but if you've established a board presence that lets you churn through dungeons quickly, doing this one repeatedly will draw you a lot of cards and net you a lot of mana.

Choice One: Goblin Bazaar or Twisted Caverns
Goblin Bazaar, unlike the last dungeon choice you made with the word "Goblin" in it, does not give you goblin tokens, it gives you a Gold token (which is what the non-Goblin choice gave you last time). Twisted Caverns disables target opposing creature until your next turn. If you've got enough Venturing Into The Dungeon going that you can clear this dungeon once every turn, you can effectively permanently disable an enemy creature by choosing Twisted Caverns every time through, which is nothing to scoff at.
Verdict: Twisted Caverns if there's a targetable enemy creature on the board, Goblin Bazaar otherwise.

Choice Two: Runestone Caverns or Muiral's Graveyard
Muiral's Graveyard creates 3 skeleton tokens; just like with the Gobin Lair, there's nothing wrong with tokens except they don't Venture. Runestone Caverns lets you pick one of your next two cards and drain half its cost in mana from your hand to fetch it and give it full mana - which is a very good effect if you have the mana to drain. If you can't drain enough mana from your hand, it'll just exile those two cards you looked at, which is irrelevant 99.8% of the time.
Verdict: Runestone Caverns unless you have some very specific reason for not wanting mana drained from the cards already in your hand (kill spells with flash, etc.)

Along the way in this dungeon, you will have gained a little life, drawn some cards (one of which got six mana) and at the end of the dungeon, you'll draw three more cards and then get to pick which of the first four cards in your hand you want to give full mana to. A definite upgrade over the Lost Mine and a pretty significant card-draw engine if you are Venturing often enough.

Tomb of Annihilation

4 Ventures to complete (can be done in 3 Ventures if you're a masochist). In pen-and-paper D&D, the Tomb of Horrors is a legendarily brutal meatgrinder (though I was in a party that really did survive it in a P&P game - that boast in the title is true!). In PQ, Tomb of Annihilation, which was clearly inspired by the Tomb of Horrors, is not quite that rough but is still by far the least pleasant dungeon to explore and I recommend going through it only once (if you're using Acererak the Archlich, or to power up Ellywick's 3rd loyalty ability if you're using her) or skipping it altogether (if neither of those situations apply).

There's only one choice to be made in this dungeon: Veils of Fear or Oubliette
Veils of Fear makes both players discard a card if they have more than 4 cards in hand, or lose 6 life if they don't. Fairly insignificant. It also leads to another room, Sandfall Cell, which will destroy each player's 3rd creature (if they have 3 creatures on the board) and cost them 6 life if they don't. Oubliette, on the other hand, only affects you, kills your last creature, makes you discard a card, and destroys a land support and an artifact support of yours. The benefit is, going the Oubliette route is one less Venture; however, a serious Dungeoneering deck will have plentiful sources of Venture and it's not going to be worth losing all that board presence just to save one Venture. Heck if the artifact it blows up is your Delver's Torch, it can cost you a Venture-per-turn just to save one Venture.
Verdict: Veils of Fear, every time.

At the end of this one, you'll get Atropal, a 6/6 deathtouch token creature, which may help make up for the creature you probably lost getting through it, but isn't a good enough reward to be worth going back through it again, ever.

If I didn't hate reading, I wouldn't need a Dungeons Guide!

tl;dr - do The Lost Mine once to get Dungeon Spoils early (pick Mine Tunnels and then Dark Pool). Then just do Dungeon of the Mad Mage over and over; pick Twisted Caverns if there's an enemy creature or Goblin Bazaar if not, and then pick Runestone Caverns next.

Only do Tomb of Annihilation if you're bringing Acererak the Archlich or using PW Ellywick; in those cases, pick Veils of Fear and only do it once!