Santa-NK1

Santa-NK1 is a Hardmode mini-boss that spawns during the Frost Moon event. When below half health, the face and beard of the Santa mask will be torn apart to reveal a rather morbid mechanical skull underneath.

Attack Phases
Santa-NK1 repeatedly cycles through three attack phases: While moving, it also drops large spiked balls on the ground that deal high damage (120-150+ with Chlorophyte armor). These increase in frequency as Santa-NK1 takes damage.
 * First phase: Chain gun fires bullets at the player.
 * Second phase: Presents launch high, then rain down via parachute from above, causing damage on contact with players. These travel through blocks.
 * Third phase: Rocket barrage. These also travel through blocks.

Tips

 * Note that his Present launch and rocket barrage attacks are highly inaccurate.
 * If you use wings you can fly over him back and forth and make it harder for him to hit you with the chain gun and the rocket barrage.
 * If you have obtained the Razorpine and Golden Shower then you can hit him with the Golden Shower to lower his defense then fire your Razorpine at him. This is highly effective with Spectre armor with the Spectre Hood as it fully heals you no matter how low you are. This seems to be even more effective on the because the Spectre Hood still has its old stats, which increases magic damage, instead of lowering it.

Trivia

 * "Santa-NK1" is a play on the portmanteau of Santa and Tank, "Santank," the name used when the enemy was first announced.
 * The image in the game files used for when the face is ripped off uses the name "SantaTank.png."
 * Its arm appears to be a large Chain Gun, an item which it sometimes drops.
 * The face and mask may be a reference to the 'Terminator' film series, as the Terminator has a metal frame and an outside 'skin'.
 * It is one of the only three bosses whose map icon does not change after entering its second phase, the others being the Brain of Cthulhu, and the Queen Slime.

History
圣诞坦克 Père Noël-NK1