Goblin Army

The Goblin Army (also known as the Goblin Invasion and the Goblin Siege) is an Event when unique Goblin enemies spawn and swarm the map's original spawn point (not the spawn set by the Bed). A Goblin invasion has a random chance of occurring at any particular dawn, if the criteria stated below are met. It can also be triggered manually using a Goblin Battle Standard.

Criteria
The criteria for a Goblin Invasion to occur at all is as follows:
 * You must have at least one person in the game with 200+ current life.
 * You must have smashed at least one Shadow Orb or Demon Heart.
 * You must not have had an invasion within seven in-game days.

Chances

 * After the spawn criteria have been met, there will be a 1/3 chance every day for the army to first invade.
 * Further invasions (after the first has been defeated) have a 1/30 chance of occurring each day in normal mode and 1/60 chance in hardmode.
 * You will see a random invasion about every 12 hours of playing in normal mode and every 24 hours of playing in hardmode.
 * The Goblin invasion takes a higher priority than the Pirate Invasion, which can only occur when the Goblin invasion fails to do so.

Initial event


When a Goblin invasion is coming, a message will appear reading: "A Goblin Army is approaching from the [east/west]!"

This message repeats a few times (Four times on a small-sized world, five times on a medium-sized world and six on a large-sized world). The direction specified in this message only pertains to the initial wave of Goblins, which spawns at the World's edge and travels to the player's original spawn point. Additional waves spawn immediately within the player's original spawn area when the player is in that area.

If the message says "West", the initial Goblins will come from the left. If the message says "East", they'll arrive from the right. Note that these directions are not related to the apparent motion of the Sun and the Moon, which, in Terraria, appear to move from left ("west") to right ("east").

When the Goblin Army is about to begin spawning around the player's spawn point, the following message appears: A Goblin Army has arrived! and the theme music will switch to the soundtrack "Boss 1."

Completing the event
The event is completed when the player(s) defeat all goblins in the army.

The size of the army is based on the count and health of the players currently in the world. There will be 80 base Goblins, plus an additional 40 for each player that has a maximum health of 200 or more. In single player, the army will consist of 120 goblins, while in an 8-player game, with each player having 200 HP or more, it will spawn 400 Goblins. With the maximum of 255 players above 200 health, the maximum number of goblins in an invasion is 10,280.

When the final wave of Goblins is on the screen, a message will appear saying A Goblin Army has been defeated!, and the theme music will return to normal after the last goblin is killed.

Other Goblins

 * Goblin Scout: An enemy Goblin that drops Tattered Cloth and spawns near the edges of the world. Tattered cloth can be collected and used to craft a Goblin Battle Standard, which is used to cause the invasion.
 * Goblin Tinkerer: A Town NPC. Appears bound underground randomly after one goblin invasion has been defeated.

Tips

 * Because the goblins will only continue to spawn at the map's original spawn point, building your home away from there may allow a player to avoid the army entirely, or until choosing to travel to it to fight.
 * If you have the Vilethorn, you can simply remain in your house, barricade all doors with blocks (any type), and attack the Goblins as they come within range of your Vilethorn. You will be safe from all attacks except for the Goblin Sorcerer; however, they will always teleport close enough to hit with the Vilethorn anyway (even if not on their initial spawn), and the Vilethorn will also repel their projectiles easily.
 * Ironically, Spiky Balls are highly effective on the Goblin Army.
 * On an open, flat space, you can easily deal with the fighters (they won't jump around and will be lined up for multiple hits) and help you get to the Sorcerer and dodge/destroy their projectiles more easily.
 * Dig a pit deep enough so the Goblin Army cannot jump out, and buy about 80 grenades. Toss the grenades into the pit, and use ranged weapons to take out the Goblin Sorcerers.
 * A more complex strategy requires several buckets of lava and a long, flat space. Choose a point roughly in the middle of this space; this is where you will stand during the invasion. On each side of this space, dig a trench 1 block deep and 10-12 blocks wide. Use the lava buckets to fill these trenches (one bucket for a twelve block trench is usually sufficient). After filling the trenches, test the lava depth by throwing a single copper coin into the lava. If your coin disappears, lengthen your trench by one block. Repeat the coin test until it no longer disintegrates in the lava. Place two wooden platforms in the air several blocks above the trenches. Make sure you can see the entire platform from your center space! If your setup is correct, the goblin army will spawn offscreen and die harmlessly in your trenches; the Goblin Sorcerers will spawn on the wooden platforms, wide open for a ranged assault; and the entirety of the loot will be waiting for you to pick up from the traps.
 * It is possible to use the strategy above without lava, using ranged weapons fired from a high platform.
 * Fighting inside a tunnel lets you force the goblins to approach from a single direction, and it neutralizes the archers (the archers' arrows are fired in an arc, hitting the ceiling before they reach you).
 * If you make two holes at the edge of your screen then the goblins will not jump over them, but instead they will walk straight in. (See the picture.)