The wandering witch is a new type of trader that spawns at night. Wandering traders struck by lightning will turn into wandering witches.
Wandering witches have 7 trades, listed on the following pages.
12 glass bottles, 6 nether wart, ominous bottle, or brewing stand -> 4 spider eyes
Rare potion ingredient -> 2 fermented spider eyes
2 spider eyes -> cauldron or 8 chains
3 spider eyes -> 5 redstone, 5 gunpowder, 5 glowstone, or 1 amethyst dust
4 spider eyes -> weakness splash potion, lengthened fire resistance potion, lengthened night vision potion, or lengthened water breathing potion
2 fermented spider eyes -> 4 slime balls or 1 ender pearl
8 fermented spider eyes -> witch hat
All the trades have four uses, except the potion and witch hat trades, which only have one use.

Just look at that stylish outfit! Perfectly matches the llama!