Terraria contains two holiday themed events, one of which being the Frost Moon. The Frost Moon is an event that can be accessed after killing Plantera and contains difficult enemies and valuable drops which help in the late-game. It also spawns a boss and two minibosses so you’ll have to go through it if you want to get all the boss trophies.
Triggering the Frost Moon
Before you can fight the enemies of the Frost Moon you need to start it. The event is triggered by using the item the Naughty Present. This is an item which can be crafted after the Hardmode Jungle boss Plantera is defeated.
The Naughty Present requires three items; 20 Silk, 5 Ectoplasm, and 5 Souls of Fright combined at a Mythril or Oricalcum Anvil.
Silk can be crafted at a Loom with 7 Cobwebs. In total you’ll need 140 Cobwebs so finding a spider cave is the best idea to craft enough Silk.
Ectoplasm is an item which drops from Dungeon Spirits. Enemies which spawn when enemies in the Dungeon are killed only after Plantera has been defeated. The Dungeon Spirits themselves are easy to kill but the Dungeon enemies they spawn from are far more difficult to take down.
Souls of Fright drop from the Skeletron Prime boss. Defeat him and he will drop 25-40 Souls of Fright to craft your Presents.
Once you have the Naughty Present, wait until nighttime and use it to begin the event.
Enemies in the Frost Moon
The Frost Moon event contains a large number of unique enemies and a unique progression system. Similar to the Old One’s Army’s wave system, the Frost Moon has 20 Waves to complete. Waves are completed by killing a certain number of enemies which increase your score. Reaching a high enough score progresses you to the next wave. You’ll have to be quick though because once the sun rises the event ends. You’ll want to do this as reaching wave 15 before morning will cause the next day and night to behave as if the game were being played during December, with Christmas enemies spawning and Presents dropping from all enemies.
The first nine enemies are effectively fodder and are
Gingerbread Men - A basic melee enemy. When killed they add 2 points to your score.
Zombie Elves - A basic melee enemy. When killed they add 1 point to your score.
Elf Archers - A ranged enemy that will shoot flaming arrows at the player which inflict the On Fire! debuff. When killed they add 3 points to your score.
Nutcrackers - A melee enemy which will change phases below half health and begin spinning as it moves toward the player. When killed they add 4 points to your score.
Yeti - A basic melee enemy which is immune to knockback. When killed they add 18 points to your score.
Elf Copters - A flying ranged enemy which will rapidly fire fast-moving bullets at the player. When killed they add 8 points to your score.
Present Mimics - An enemy which behaves identically to other mimics however it is disguised as a present instead of a chest. When killed they add 20 points to your score.
Flockos - An enemy which tends to spawn alongside the Ice Queen and will fly toward the player at high speed. Does not reward any points when killed.
Krampus - A basic melee enemy. Does not reward any points when killed.
The final three enemies are minibosses and bosses
Everscream - Very similar to the Pumpkin Moon’s Mourning Wood miniboss. It will fire volleys of needles and lingering ornaments at the player. When killed they add 50 points to your score.
Santa NK1 - The Santa NK1 (or SanTank) is a miniboss with a multitude of different attacks. They can fire a chaingun at you, similar to the Elf Copter enemies. They will also randomly drop lingering Spiked Balls the more its damaged which stay on the ground and deal high damage. They can also fire rockets at the player which can travel through walls. Finally they can launch a barrage of presents into the air which float back down slowly and deal a high amount of damage.
When below half health their sprite will change to show their face ripped off, revealing a mechanical skull. When killed they add 100 points to your score.
The Ice Queen - This is the main boss of the Frost Moon and she has three phases. She will fly across the screen shooting Frost Waves at the player. Then she will try to stay above the player while dropping down Frost Shards. Then she will stay stationary, spinning and throwing out Frost Shards in random directions. As her health goes down she also begins moving faster. When killed she adds 150 points to your score.
Drops of the Frost Moon
The only fodder enemy with drops is the Zombie Elf which drops the Elf set.
Drops from the Everscream
Christmas Tree Sword - a Melee class sword which shoots a slow moving star toward the cursor which spawns a number of floating ornaments as it goes. The ornaments will fall to the ground after a short time.
Razorpine - a Mage class weapon which shoots out gravity affected needles at an extremely fast rate. Effective when used with the healing version of the Spectre Armor.
Festive Wings - a set of christmas tree themed wings.
Christmas Hook - a christmas light themed hook.
Shrub Star - a pet item which, when equipped, will summon a Everscream Sapling pet to follow you. Only drops in Master mode.
Drops from the Santa NK1
Elf Melter - a Ranged class flamethrower which uses gel as ammo.
Chain Gun - a Ranged class gun which shoots incredibly fast but has a wide spread and is very inaccurate. Effective when paired with the homing Chlorophyte Bullets.
Toy Tank - a mount which, when used, summons a Santank Mount which behaves similarly to the Unicorn mount and even includes a double jump. The mount is equipped with an auto-targeting chaingun and rocket launcher which fire at enemies in front of you. Only drops on Master mode.
Drops from the Ice Queen
Blizzard Staff - a Mage class staff which summons Blizzard projectiles from the top of the screen toward the cursor. Behaves similarly to the Meteor Staff or Daedelus Stormbow.
North Pole - a Melee class spear which fires a gravity affected North Pole Spear projectile which then spawns gravity affected snowflakes as it flies.
Snowman Cannon - a Ranged class rocket launcher which fires Snowman Rockets.
Baby Grinch's Mischief Whistle - a pet item which, when equipped, will summon a Baby Grinch pet to follow you.
Reindeer Bells - a mount which, when used, summons a Rudolph Mount which behaves similarly to the Unicorn mount and includes the ability to fly.
Frozen Crown - a pet item which, when equipped, will summon a Cursed Sapling pet to follow you. Only drops on Master mode.
It's recommended to create an arena with a pit filled with traps. These traps can be collected from the Temple in the Jungle biome and will deal with the smaller fodder enemies and Everscreams while you can focus on the Santa NK1s and Ice Queens.
In a Nutshell
The Frost Moon is a post-Plantera event summoned by using a Naughty Present at night. During the event a number of unique enemies will spawn which will drop valuable items for Mage and Melee classes. Though you have to be quick as once the sun rises the event is over and enemies stop spawning.
Can I use my Pumpkin Moon arena for this event?
Yes! These two events are so incredibly similar that using the same, trap filled arenas is recommended. It cuts down on time and makes fighting both of them in quick succession simple.
What weapons are best to use for the Frost Moon?
Good weapons to use are ones that are effective at crowd control as well as single target damage. Many of the Frost Moon enemies have huge health pools so dealing lots of damage on the tankier enemies is more important than dealing with crowds. Though it's still important to take care of crowds to allow more enemies to spawn. The Influx Waver and Seedler are effective melee weapons which have high single target damage. Tsunami with Holy Arrows are also effective. The Razorblade Typhoon is definitely one of the best items to use due to its piercing and homing abilities as well as its effectiveness on single targets.
What is the best item to get from the Frost Moon?
If you’re playing Mage, the best weapon to get by far is the Razorpine. It does immense amounts of damage with the right setup. For melee, both the North Pole and Christmas Tree Sword are comparable so pick whichever you like. The other classes don’t get much from this event unfortunately but the Pumpkin Moon event has far better drops for Summoner and Ranged, so try that instead if you use those classes.