Diabolist

The Diabolist is a Hardmode enemy found in the post-Plantera Dungeon. It is most common in areas backed by Tiled Walls. These are identified by the related Faction Flag, the Diabolic Sigil.

Diabolists attack by firing blazing magic bolts that can travel through blocks at the player. Their magic bolts explode, creating an "inferno", a large flaming sphere that lasts for nearly 4 seconds and deals massive damage on contact, inflicting the On Fire! debuff. Diabolists teleport to a different location on-screen every time they are hit.

Tips

 * Since a Diabolist's shots go through solid blocks, taking cover is usually not an option.
 * Weapons that stick to enemies are exceptionally useful, as they remain on the Diabolist after the teleport. The Piranha Gun,, and are viable options.
 * Weapons that deal high damage in single hits are effective against Diabolists. Weapons that fire multiple projectiles simultaneously may be able to land multiple hits before they teleport as well.
 * Weapons with homing capacities or minions can continue to track Diabolists after they teleport.
 * Like other caster AI, Diabolists cannot teleport to any space less than 4 blocks or more than 20 blocks from your feet, will not teleport to blocks covered in lava, requires at least 2 solid blocks(or platforms) and 2x3 clear space to teleport to, and it will not attack if constantly damaged.    These facts together can be used to set up a safe dungeon farm if the only space they can spawn in/teleport to has a pressure plate with spiky ball traps.