In the Nexus, many players will trade items, and because of this, on the most crowded server, sometimes the lag is overpowering and you may be disconnected. The Nexus is also the access point to many other places like your vault, the realms, Pet Yard and there is also a statue where you can change your name. Aside from trading and access to other places, you can also make in-game purchases from Kabam with realm gold, which you can buy with real world money. Purchases can include High-end armours, weapons and abilities, consumables such as drake eggs and pet eggs and, in the Cloth Bazaar dyes and textures for aesthetic changes to your characters outfit.
Annoyingly, and unsolved by Kabam, there are a vast amount of advertising bots within The Nexus, and these bots play a significant part to the lag that is caused to the server. These bots normally advertise websites where you can buy equipment for the game (for real money).
These bots appear as randomly-named wizards sporting nothing but Energy Staffs and Fire Spray Spells (Tier 0 equipment). They will ignore attempts by players to trade and will usually walk back and forth along the main aisle of Nexus connecting the portal spawning area and the area containing items to sell and guild, vault, and pet yard portals.
Sadly, the Nexus is a target for hackers. On 9-7-13, SwatSecOne hacked the Nexus to spawn Oryx, Candy Butterflies, and other boss monsters on the spawn of the nexus. It has killed over 2,000 (estimated) people.