Encounter Help

[Ramshack]

So I've mentioned a few times in the forums that I'm working on a Diablo Inspired Campaign. I'm having a fun time converting the games bosses into custom encounters using the MM's Lair and Legendary Mechanics to make interesting and hopefully memorable fights for my players.

Now I want to bring the same kind of interesting fight to the end of the level 1 adventure hook. Basically the adventure's arrive in Tristram and meet a few NPCs at the Tavern of the Rising sun, they learn about the strange creatures and missing prince Albrecht. Albrecht was reportedly captured and taken into the catacombs beneath the Cathedreal of Light.

The level 1 adventure hooks takes the adventurers through the first level of the Cathedral of Light while the search for the basement entrance. The goal is to create a creepy and haunted feel and the encounters avoid dealing with direct monsters for the first part, bat and rat swams, a shadow that stalks one of the hall ways, animated objects in the kitchen (reflavored swarm) and a few traps, holy water that turns to acid, falling statues that kind of thing.

My problem is when they do find the basement entrance. I would like to have it sealed, or protected by a mini boss. Though I'm having a hard time coming up with an appropriate encounter.

As an example of what i'm putting together the level 2 mini boss is the butcher. I am using the Undead Minotaur as the base template for the creature. Only in addition he can cast thorn whim (reflavored as a meat hook) as a bonus action and then attack with his cleaver. In addition to that his lair is divided in 4 quadrants (4x4 each) each turn on initiative 20 i roll a d4 and the corresponding quadrant catches fire. As a legendary action he shove a creature. I think this creates a really unique encounter using legendary actions and lair actions.

I'd like to find something as memorable at level 1 but not make it impossible to overcome. low HP values are a real concern. So far I'm using a reflavored Sea Hag, to use horrific appearance, the idea is they walk in the room and the body of an acolyte or guard twists and tranforms into a twisted abberition. The sight of the transformation triggers a fear save via the horrific appearance rules.

However besides that I can't think of any interesting mechanics to bring to a low level fight.

[Arzanyos]

Here's a kinda crazy half idea. The party gets to the basement, only it's not there. Instead, there's a whole bunch of pulleys and platforms attached to them by rope, kind of like a room where all of the floor is elevators. The basement is door is about halfway down the elevator shaft, on the other side of the room. Also, there is some sort of ghostly swordsman(note: not incorporeal) in the middle of the room.

The idea is: you have to fight the guardian, but the floor is unstable and parts of it keep moving up and down. As well, the guardian will sometimes, instead of attacking the party, cut through the ropes of the platforms, sending anyone on them plummeting down. Fortunately, there are ropes everywhere, so if the party is quick enough, they could be able to reattach the platforms they're on, or at least not fall all the way.

Edit: Ideally, there'd be a ramshackle pattern of platforms a while down the elevator shaft, so if you can't catch hold of something, you just get stuck below everybody else. Plus, then the party can systematically remove platforms from the different levels and shove the guardian the whole way down.