Base game dungeons are badly outscaled, even on veteran/hard mode, and the last thread on this just got locked so I think it's time for a new one.

There should be a third tier of dungeon difficulty, starting with the initial base game dungeons (FG1, Spindle 1, BC1) and expanding from there. They should focus on boosting bosses by adding extra mechanics and slightly reshuffling existing ones. (As well as boosting damage and HP to the standards of a new release vet/vhm dungeon, these are still the bottom of the new difficulty curve so they should target close or just below current vet difficulty).

The dungeons should require a full clear (all bosses) in order to produce rewards, and should have two main components:

1. Perfected Monster Sets. The hat drops in the dungeon, and the boss also provides a soul fragment where a certain number of soul fragments (3 or 5) can be used to upgrade an existing shoulder to perfected. A Perfected monster set using both pieces should have roughly the same power budget as a 1pc+Mythic, so they become competitive with existing options.

2. Cosmetics. Flashy cosmetics to show off your completion. Rare drop but always available not in rotation like existing boss motifs.

To give a few examples of how this sort of thing could look in practice, let's consider Spindleclutch 1 and what sort of thing could be done to beef up the encounters for a new mode:

1. Spindlekin. There are three of them now. When one is killed the surviving ones will try to feed on it, they need to be interrupted or they enrage. If the feeding is interrupted the corpse will explode after a short delay for sigificant damage, so interrupt and get out.
2. Swarm Mother. Summons more trash. The trash does low initial damage but inflicts a long term consequentially damaging sticky DoT that needs a purge.
3. Cerise the Widowmaker and Big Rabbu. They are now together as a single encounter in the main part of the room Rabbu would be in. They perform a combo channel causing a wipe if they are close together for too long. Rabbu will stay still and chain in players who do not have aggro from Cerise, Cerise will move but will occasionally charge to where Rabbu is dealing damage along the way then return to whoever has aggro. Healers will occasionally join the fight and have to be removed. Whichever is killed first goes into an invulnerable spectral state (previewing the Praxin fight in Spindle 2) which can no longer be damaged and does greatly reduced damage but causes stuns and has to be positioned to avoid the wipe channel.
4. The Whisperer. The floor explosion leaves a lingering DoT zone for a few seconds. Arachnophobia channels for a few seconds building up an energy ball then fires at everyone not a single player.

That would be a combo of just "the boss, but harder now" and "a new boss made from minimal new components" that should be able to justify calling itself a harder version of the dungeon. Feeling familiar but novel.