Ylialkemisti

The High Alchemist (in-game name Ylialkemisti) is a boss encountered in the Ancient Laboratory, to the west of the Dark Cave. It guards the Abandoned Alchemy Lab. Though the High Alchemist moves very slowly, its powerful projectile attacks can be hard to dodge, and it is a fearsome foe for any player who decides to traverse the Ancient Laboratory.

Behavior
The High Alchemist will remain idle in the center of its arena until the player approaches, at which point it will become aggressive, and the fight will begin. Be wary, as the High Alchemist can see the player about a full screen away, and may begin attacking before the player sees it.

The High Alchemist moves by floating around very slowly, pursuing the player in a manner similar to Limanuljaska and the many other floating enemies of the world. It passively generates a special shield around itself - any projectiles that the player fires at this shield will be redirected at the player, dealing damage. This shield turns off and on at even intervals throughout the fight, and the player must take care when to fire their wands.

While the player is in its sight, the High Alchemist will periodically fire a bouncy, homing orb projectile, which dissipates after a short time. As the orb travels through the air, it will summon three large, ethereal wands that aim at the player before firing, telegraphing their attacks similarly to the Intense Concentrated Light spell. There are four different types of ethereal wands the High Alchemist's orbs can summon, and each orb will only summon one type of wand.

Dark Wand
A ghastly purple wand that fires a tight cluster of fast, potentially-bouncy beams; nearly identical to the above-mentioned Intense Concentrated Light spell. Very deadly in enclosed spaces, especially if all three instances of the wand are angled properly.

Glowing Wand
A shimmering white wand that fires a burst of explosive lasers, similar to the Pinpoint of Light spell. The lasers can cleave through most terrain, and are likely to hit the player if they are hiding behind fragile cover.

Volatile Wand
A fiery orange wand that shoots a Meteor at the player. Can set the player on fire, and can even instantly kill the player on a direct hit unless they have accrued a large amount of HP.

Thunder Wand
A cyan electrical wand that fires a Lightning Bolt at the player. Although short ranged, it can be terrible in closed spaces, stunning the player, and leading to deadly follow ups.

Rewards
Upon death, the High Alchemist will violently dissolve into a cloud of magic particles, leaving behind an Extra Max Health upgrade and a Crystal Key. The following Spells will be permanently unlocked for the player, and it will also drop 4 random spells from the full unlock list:

Combat Tips

 * Be very careful about your position throughout the fight - each time a wand spell is spawned, it will be aimed directly at where you currently are, and then fire after a short delay. Prediction of when, where, and how the wands will fire is key to survival.
 * Each summon orb will summon multiple spectral wand spells, aimed at where you are when that spell is cast. Take care that avoiding the first attack does not leave you in the path of the second attack.
 * Unlike a typical projectile shield, everything that hits the High Alchemist's shield will be reflected at the player. The Tentacle spell can be very deadly towards the player if reflected, but can still be very effective against the High Alchemist when the shield is down. However there is no animation when the shield activates so it is advised to only go in for damage shortly after the shield is gone, then stop and wait for it to go up again.
 * The High Alchemist tends to raise its shield a brief moment after receiving damage, so rapid-fire attacks will only hit a few times before the remainder of the volley is directed back at the player. Try to rely on high-damage shots rather than high fire rate.
 * If you have ways to increase your movement and flight speed such as Hastium or the right combination of Perks, you can fly around the alchemist in circles and consistently avoid the wands, shooting when his shield is down.
 * The High Alchemist will easily erase large amounts of terrain to get to the player, if necessary.
 * Patsas can be lured in from the Ancient Laboratory and can fight the High Alchemist on its own, as Patsas are immune to all of its attacks.

Parallel Worlds
In Parallel Worlds, the Alchemist's Shadow (or Alkemistin Varjo) can be found anywhere on the surface, along with the shadow version of Sauvojen Tuntija. These pink-shaded copies do not drop anything besides gold.