- Engineer (or Gnome. Unconfirmed - Goblin?) - Arcane Power Conduit - deactivates the Constructs in the dungeon, making them yellow and stunning them. They can still be damaged, and this puts you in combat with them, so you have to kill them regardless if they're part of a pack you're fighting.
- Alchemist - Interact with the Flask of the Solemn Night before pulling Patrol Captain Gerdo. When he goes to drink it at 25% health, it will instantly kill him.
- Enchanting - The Magical Orb will give the party a 20% increased damage dealt buff.
- Tailoring - Speaking to an NPC that occasionally spawns near the 2nd boss area will pull Imacu'tya away from the boss pack
- Inscription - Waterlogged Scroll grants the party 35% movement speed
- Leatherworking - Bazaar Goods will make a loud sound and call over a mini-boss from the second boss fight
- Herbalist - Umbral Bloom grants the party 25% Haste
- Hunter - Interact with the Discarded Junk near the 2nd boss to create a trap. This will draw the Beholder type boss add over to the party. Kiting him over the trap immediately kills him.
- Warlock - Interacting with the Fel Orb grants the party Fel Surge, increasing crit chance by 25%
- Priest - Interact with the Infernal Tome near the 2nd boss to grant the party 25% reduction on incoming damage
- Shaman - Waterlogged Scroll grants the party 35% movement speed
- Druid - Umbral Bloom grants the party 25% Haste
- Rogue - Interact with the Flask of the Solemn Night before pulling Patrol Captain Gerdo. When he goes to drink it at 25% health, it will instantly kill him.
I've heard that Monk interactables have been found too, but I haven't seen them myself. I also saw some Nightborne Refreshments that maybe are for Mages? But there wasn't a Mage in my group that time.