MidBoss

As you play the game, you will find some odd looking potions with labels in the bottom, using these will activate the retro filters, use each of the 12 different variations to collect them all. You can buy them from the merchant sometimes, make a list or train your memory.

*EGA, Apple II, Vic 20, GB, P&P, C64
*Six CGA modes
(use CGA potions until you get them all, the cga potions have the same label but you can notice if youre missing one if it doesnt say unlocked)
CGA Mode 4-1 Hi
CGA Mode 4-1 Lo
CGA Mode 4-2 Hi
CGA Mode 4-2 Lo
CGA Mode 5 Hi
CGA Mode 5 Lo

Hit an anvil 200 times throughout all playthroughs.

There is always an anvil on the first floor and if you are starting a new game, you will deal 1 damage.

The anvil will break after 20 or 25 damage, so you can do this achievement in under 10 minutes if you just restart a new game and go for the anvil.

The skeleton has a skill called reanimated which gives you a chance to resurrect after being defeated, if this triggers, you will get this achievement.

Equipping a Bone Armor doubles the chance of this.

This might also trigger if you play and die on narrative mode.

You need to activate the shop from the merchant at the first floor and buy the Golden Ticket in his shop.
[spoiler]
This can be easily done on new game+ with your previous abilities enabled.
Use Charge on the merchant from afar and if you are lucky, you will go into the door and glitch him out, after a bit, you will enter his shop and you just need to buy the golden ticket, Charlie!

You can also use Blink and target the stairs if you have equipped a Temporal Ring.
[/spoiler]

On Floor 15, in the 3rd room, you will encounter them, they will run away.

Go back down to the 14F, they are hiding in the storage room to the right.

Beat them up.

You can kill your own minions to get this.
Using conscript ability from the Lich lords and Fireball from Warlock, go back to Floor 1 and conscript until you fill a room, make sure your fireball does at least 20 to 25 minimum damage then let it rip.

Wont count if you die too.

First, fight the lich lords and gain access to conscript to make a minion appear in front of the door, then use Stomp to push them through it.

Going into the void has a chance to take you straight to the ending.

Some monsters only appear once in a run (RNG), so be careful of not killing a type until you master it.

Mastering the merchant is not required for the achievement.

Starting with masteries by trying for this on a new game plus wont unlock it.
However, you can unlock this on a new game+ with just your items and equipment, just uncheck masteries and abilities.

Cultist and Larva are the rarest enemies, Maggot only spawns if you hit a rotworm.

Things that drop yarns have a chance of lucky drops that are set when the dungeon seed is created, so the same run will have the same lucky drops. Yarn piles are more likely to trigger lucky drops but I got mine from a chest.

A hidden description achievement.

On Floor 13, you will find these bosses, they will attempt to fight you one by one, ignore this and attack one of the other two, they will all attack you at once, if you win, you will get this achievement.

Good luck!