Santa-NK1

There is no item that calls it. It belongs to the Frost Moon, so you set the event off at night with a Naughty Present and then fight your way to the seventh wave before it appears at all, and none of that is available until Plantera is down. Because it arrives that deep into the run, every one you kill also shoves the wave counter along hard, and the later the wave you kill it on, the better what it leaves behind gets.

It does not cycle between moves. All four run on their own timers and overlap constantly. The arm-mounted gun keeps a stream of bullets on you. Missiles arrive in barrages that ignore terrain, so walls do not help. Presents get lobbed high into the air and drift down under parachutes, hurting anything they touch on the way. And it drops a spike ball at its own feet. Every one of those speeds up as its health falls, in steps rather than smoothly, so the fight quietly doubles in volume around the halfway mark and again near the end.

Everything else is chip damage by comparison. The ball hits harder than any other single attack in the Frost Moon, harder than most real boss attacks in the game, and on Master it will take a well geared player from full to dead on contact. It lands on the ground beneath the machine, which is the whole argument for never fighting this thing on foot.

The missile and present barrages are wildly inaccurate, so they read as screen clutter rather than aimed attacks and mostly punish standing still. Long horizontal passes on wings, back and forth past it, make the gun and the missiles miss almost everything while keeping you off the ground where the spike balls land. The one thing you cannot do is settle into a spot. Remember the rest of the wave is still happening around you, so any dodge route has to account for whatever else the moon has sent.

Strip its defense first with a Golden Shower or Betsy's Wrath, then hold a Razorpine on it. That pairing is the standard answer because the Razorpine floods the airspace it occupies and does not care much about your aim. Spectre armor with the Spectre Hood converts that damage into healing fast enough to cover the hits you are going to take anyway, which matters more than raw kill speed when the fight is happening inside an ongoing event.

Below half health the Santa face and beard tear away to expose the machine skull underneath. No new attack comes with it, so treat it as a health gauge in a fight where you get no boss bar. Its map icon does not change at the same time, which is unusual: almost everything else in the game switches icons when it flips phase.

The name compresses Santa and tank, and it was announced as Santank before release. The torn face sprite is still filed under that older name in the game files. The exposed skull is a straight Terminator nod. Its weapon arm is a real Chain Gun it sometimes hands over, and on Master it always leaves a relic plus a decent chance at a drivable Toy Tank. The Pumpkin Moon has no counterpart for it, unlike Everscream and the Ice Queen.