Pylons

Pylons are furniture items. They allow a player to teleport to any other pylon with the following restrictions:
 * Pylons can only be used when there are 2 or more NPCs nearby.
 * Pylons are only practical if there are 2 or more in the world. The system they form is known as the pylon network.
 * Pylons only function when in the matching biome.
 * Only one of each type Pylon may be placed in a world.
 * The pylon network cannot be used during Boss battles or when invasions are announced or in progress.

Pylons are sold by NPC vendors, and have interactions with the Town mechanic. The pylon can be sold by every NPC in the biome, as long as they have high enough happiness. Every NPC has a specific biome preference, building a house for them in their preferred biome increases happiness.

Types
Pylons have a corresponding biome. They may only be sold by NPC vendors who are living in that biome. Additional requirements before pylons will be sold may include number or happiness of NPCs in the area.


 * Cavern Pylon
 * Forest Pylon
 * Snow Pylon
 * Jungle Pylon
 * Desert Pylon
 * Ocean Pylon
 * Hallow Pylon
 * Mushroom Pylon
 * Universal Pylon

NPC Happiness
Pylons are only sold by NPCs when their happiness is high enough, so here are some ways to increase their happiness:


 * Place NPCs next to other NPCs that they like. This takes maximum effect not just when NPCs that like each other are in the same town, but are in different rooms in the same building, connected by doors or platforms.
 * Place NPCs in biomes that they like.

If an NPC's happiness should be maxed out, but they aren't offering pylons, their houses are likely too far from each other.