To start with, we need a "Random Delve Finder" that pairs us with people, or we can group up and then queue, but essentially we just get put into a random delve, run it and get a decent / appropriate reward.
Customizing the delve would come through checkboxes in the matchmaking menu.
Some options would probably be grayed out with eachother... Like you wouldn't see Animal Pictograms in a Dwemer Ruin, and you wouldn't see fire traps in a Valenwood Cavern.
Here's an example of how it would look, and how a Delve might be customized for specific adventure.
Location:
[ ] Random
[ ] Ayleid
[ ] Dwemer
[ ] Daedric
[X] Cavern (Valenwood)
[X] Cavern (Skyrim)
[ ] Cavern (Morrowind)
[ ] Cavern (Elsweyr)
...
Enemies:
[ ] Random
[ ] Ghosts
[ ] Wraiths
[ ] Skeletons
[X] Trolls
[X] Goblins
[ ] Dwemer Constructs
[ ] Bandits
[ ] Trolls
[X] Ogres
[ ] Harpies
...
Bosses:
1: [Large Troll]
2: [Goblin Mage]
3: [Select Creature Type]
Additional Challenges:
[ ] Random
[X] Puzzles
-[] Constellations
-[ ] Animal Pictograms
-[x] Crystal Alignment
[ ] Traps
-[ ] Spikes (Ground)
-[ ] Spikes (Wall)
-[ ] Fire (Ground)
-[ ] Fire (Wall)
[X] NPCs
-[x] Escort Adventurer
-[x] Free Captives
-[ ] Cure Afflicted
-[ ] Break Enchantment
...