Guide:Arena

An Arena is generally an area that the player builds where they can face a Boss or other significant challenge more easily. Each arena can be different for each boss, some consisting of a flat area or multiple layers of Platforms supported with Statues.

General Arenas

 * An arena is better built away from Bases so NPCs won't get hurt or killed. It's better built near the ground, far from Space so there won't be any unwanted or  spawns during an important fight.
 * A typical arena usually consists of multiple long rows of, or a flat surface on the ground or the air made out of to greatly increase running speed.
 * Sometimes, the shape of the arena depends on the Boss or Event and how the player decides to fight it. and  can be used to easily kill enemies from Events, while certain bosses like King Slime lack the ability to attack through solid blocks (although as of update 1.3.0.1, King Slime will teleport directly to the player if he gets stuck on blocks).
 * Placing, , placed in  and  will greatly increase Health regeneration in battle. A Mage may also want to place  and  to regain Mana more easily.
 * reduce enemy spawn rate, which may help on bigger arenas - however, in many scenarios such as farming events, an increased spawn rate is more favorable.
 * Water Candles increase enemy spawn rate, which will help when fighting timed events such as the Pumpkin Moon - keep in mind, though, that fighting bosses or untimed events will be more difficult.
 * You can build a house for your NPC near your arena. The House should have a, so in the middle of the battle you can use a  or  to visit the Nurse and get instant healing. The house is better built away from the arena to prevent the Nurse from being killed.
 * A can be used to increase defense of nearby players. It is found in the underground desert.
 * Since luck increases damage, it's helpful to place luck increasing items like s and the corresponding biome's Torches.
 * Once you have killed Skeletron and had the (or on versions prior to 1.4.4, a Mechanical Boss and had the ) move in, you can buy and use  to devastating effect. When wired to a  placed above them, you can instantly transport across the arena as soon as you walk on them, greatly increasing mobility. They could also, alternatively, be used to teleport to the Nurse, heal up, and quickly return to the arena.

Advanced Arenas

 * If using the Nurse is something that you are planning to do, create a three block high valid NPC house directly underneath your arena and move in the Nurse. This way, you can still right-click her easily since she is right underneath you and still run right by without having to enter a building that could trap you.
 * Try building your arena so the center is at your natural world spawn, that way if an event occurs you can easily teleport there by unsetting your spawn point from your bed and using a Magic Mirror or Recall Potion. You will teleport directly to the arena so you can get in the fight right away, and if you die you will respawn right there again. Try combining this with the above strategy so you can respawn after death right at the Nurse to heal yourself the rest of the way.
 * If you are going to be moving the Nurse into your arena, it is a good idea to move the Arms Dealer into a nearby or adjacent house so the Nurse will be happy. This way, healing from the Nurse will cost much less than if she was alone, and you can easily buy more ammunition from the Arms Dealer if you run out.

The Destroyer
Using a Daedalus Stormbow with Holy Arrows can be extremely effective due to the Destroyer's length making it easy to hit. Making a sky arena is also very effective, making it so that the Destroyer is unable to hit you. in the 1.4.4.9 (to my understanding) if the destroyer is out side of your view he can fly to get you so watch out!!!

General Invasions
Invasion events such as the Goblin Army, Pirate Invasion and Martian Madness can only be fought near the Spawn, or somewhere close to an NPC.

Before starting an event, make sure NPCs are protected, otherwise they will be attacked and possibly killed during the fight. Placing a block in front of a Door will prevent enemies from forcing them open and killing the NPCs.

If defended properly, the events can then be easily fought on a player's Base, using the Houses built as cover. Since most enemies from invasions lack the ability to attack through walls, they can be easily killed while standing above them in an enclosed room. However, make sure to have an exit ready for when the enemies that can attack through blocks spawn.

Moon Events
The Pumpkin and Frost Moons are much easier to handle with the proper arena.

A flat surface about 168 blocks wide (See NPC spawning) will focus all spawns on the arena. Above it there should be a long platform of the same width, high above the ground in order to keep grounded enemies out of reach.

Since the player will mostly focus on the Bosses on the later waves, Lava pit and Traps may be helpful to take out the weaker enemies more easily. However, on higher difficulties the Traps' low damage is practically useless against the higher-health enemies, making them almost a liability due to the invincibility frames they provide and the risk of being hit by them and taking massive damage in the process.

It's also a good idea to make a room with a near the Arena, so in case of death you can quickly get back to it.