All mobs are split into the "normal" and "tough" category. Each chamber has 3 normal mob spawners and 1 tough mob spawner. A good amount of the mobs have been altered for balance and convenience.
("O." is short for "ominous")

Normal category

Zombies
  O. adds rebalanced armor and ench. bows

Husks
  ^

Drowned
  ^

Skeletons
  O. adds rebalanced armor and ench. bows

Strays
  ^

Bogged
  ^

Spiders
  O. changes some spiders to cave spiders

Slimes
  O. changes to magma cubes

Pillagers
  O. replaces arrows with powerful rockets

Vindicators
  Base attacks with hands
  O. gains wooden sword

Zoglins
  O. increases damage and knockback

Creepers
  O. changes to (nerfed) charged creepers

Phantoms

Trident Drowned

(baby zombies and silverfish are completely removed)

Tough category

Base vaults are split into three: armor, valuables, and weapons. This will let you (partially) customize your loot and opt out of stuff you don't want. All 3 vault types will always be found grouped together. The structure will generate plenty of these incase a player wants to use all of their keys on only one category. Luck adds a 33% chance to dispense double the loot. Aesthetic based loot (sherds, banner patterns, trims) are moved to hidden chests in intersections so that they don't get in the way of the more useful vault loot.

Armor table

Valuables table

Weapons table

Ominous vaults are still a single category. You will get both types of keys from ominous spawners so the ominous vaults will act as an enhancement to the loot the other vaults give you. 

Ominous table

Pots can hold wind charges or less valuable ores, such as lapis, copper and redstone. You'd likely find this structure while mining, so this is meant to synergize with that. 

Tridents and heavy cores are reserved for bosses. Once defeated, the main boss spawner will dispense a trident on normal difficulty or a heavy core on ominous. This gives you a 100% chance of getting these items per trial chamber (unlike the very low chances per vault from vanilla) in exchange of the added difficulty from the bosses.

Food will be dropped by tough mobs instead of them filling up vault loot tables. 

This is something I particularly want to balance well, so feedback would be appreciated!

Corridors 

• Pots, vaults and doors to chambers line the walls
• Arrow and fire charge dispensers that can be shot at spawners
• Only part of the structure where the amount of spawners are random
• Dripstone can generate on the bottom to punish falling from the higher levels
• Spawners can have zombie variants, skeleton variants, spiders, slimes and pillagers

Ledge (originally called chamber 1)

• Similar ledge layout but platforms are lower
• Normal spawners: skeleton variants
• Tough spawner: jockeys

Trench (originally called chamber 2)

• Original was just ledge but with powder snow, this is a new layout with a powder snow pit on the bottom
• Holes and trapdoors to drop down mobs
• NS: zombie variants, spiders, zoglins
• TS: big slimes

Cubic (originally called chamber 4)

• Basic layout like original but randomly generated
• NS: zombie variants, zoglins, slimes
• TS: wither skeletons

Crawl (originally called chamber 8)

• Mostly unchanged from original but added wind charge launchers to get to the next floor for fun
• NS: skeleton variants
• TS: ranged wither skeletons

Eruption

• Press every button on all 4 sides of the room to make lava pour from the center in a guided path
• NS: vindicators, slimes, pillagers
• TS: breezes

Pedestal

• Original had every spawner clumped in the center with a lot of random and strangely generated gaps, this version fills those gaps and seperate the spawners a bit so you don't activate them all at once
• NS: zombie variants, slimes, pillagers, phantoms
• TS: witches (remember: honey bottles cure poison)

Assembly

• Fight a breeze on the bottom, climb up the parkour section at the back, then fight ranged mobs on the hanging platforms at the top
• Bottom section has traps for breezes to trigger such as potion dispensers, trapdoor pits, and deadly rocket dispensers
• Throw wind charge on the hanging platforms to expand their size
• NS: zombie variants (bottom), skeleton variants, pillagers (top)
• TS: breezes

Slanted

• Chamber is split into mini chambers in each corner designed for fighting a specific mob type
• More of a maze-like layout between enemy rooms
• NS: skeleton variants, spiders, phantoms, vindicators, drowned
• TS: vexes

Ladder (new!)

• Climb up the ladder of platforms, each with a spawner, along with blazes shooting at you from the top
• Create staircases with the chiseled copper mechanic
• Knock mobs down the middle to land on dripstone
• NS: spiders, zoglins, pillagers, slimes
• TS: blazes

Channel (new!)

• Water themed chamber
• Soul sand shoots mobs above water incase you try to escape
• NS: drowned, trident drowned
• TS: guardians

Crash (new!)

• Explosive themed chamber about destroying the terrain you fight on
• Chamber is trapped to punish reckless explosions
• Ghasts shoot you while kept in place
• NS: creepers, zombies
• TS: ghasts

Boss chambers will always generate at the end of the structure. Currently there are 2 chambers, but more are planned. Boss 1 is about fighting a medley of every mob in the structure with powerful dispensers and traps. Boss 2 has you fight a ravager while it plows through the leaves that fill the room. Breezes also shoot at you to make you disoriented. Defeating a boss on normal difficulty will reward each player a trident. Ominous difficulty will give a heavy core instead.