Pumpking

The Pumpking is a very hard hardmode boss that spawns during the Pumpkin Moon. It behaves very similar to Skeletron. It has two lengthy arms each with a large scythe. These hands act much like Skeletron's hands.

Considered the Final Boss of the Pumpkin Moon, subsequent waves after its appearance increase the number of mobs. There can be a large number of these at once in later stages (Final Wave 15, up to 7 active at the same time (over 7 in multiplayer).

Like Mourning Wood, the later the wave Pumpking is killed in, the more likely it is that it will drop an item. Note: the probabilities that each item will drop are independent of the probability that any item will drop.

Pumpkings that are defeated in Wave 15 are guaranteed to drop an item, as well as their Trophy.

Strategy
The Pumpking has 3 "phases", which it will cycle through at random. A player can tell which phase the Pumpking is on based on its facial expression. When the Pumpking is transitioning to a new phase, its head will rotate (see image below).

During the first phase, its face will resemble a typical jack-o-lantern, with a sinister-looking grin and downward-facing eyes. In this phase, it will chase you more closely than the other phases, and attack with its scythe arms more aggressively. In this phase, the Pumpking is almost identical to Skeletron Prime, so the same strategies will apply.

During the second phase, its face will look angry, with its mouth wide open in the shape of an 'O' and upward facing eyes. It will follow you from a longer distance than the first phase, and it will spit out "Greek Flame" projectiles. These projectiles are very easy to dodge, because they are fired with almost no force, so they will only fall down at an angle. However, they will stay on the ground for a short while and damage you if you walk over them. Stay above or to the side of the Pumpking during this phase and you will remain mostly unharmed.

During the third phase, the Pumpking's eyes will be open, and its mouth will be fairly wide. In this phase, its scythe arms will fire projectiles at you. Similar to the Demon Scythe, the projectiles will stay motionless for a few seconds, and then they will begin to spin, and fly towards you at increasingly fast speeds. The projectiles are very large, and can be hard to dodge. Keep your distance from the Pumpking during this phase if you want to avoid damage.

Trivia

 * The Pumpking's changing faces might be a reference to Demonhead Mobster Kingpin from Problem Sleuth, The Mayor of Halloween Town from The Nightmare Before Christmas, or to the Dodecahedron from The Phantom Tollbooth, or the Quintessons from the 1980's-era "Transformers".
 * One of the Pumpking's drops (Explosive Jack 'O Lantern) is possibly a reference to the pumpkin bombs used by the Marvel Comics-character Green Goblin.
 * The Greek Flame attack is a reference to "Greek fire", a sort of antique flamethrower used by the Byzantine Empire.