Editing Terraria (section)

===Old One's Army===
A crossover with some tower defense game called Dungeon Defenders 2, and basically plays like one somewhat. Except you can fight the enemies in the waves head-on yourself if you want. Notably gets upgraded as you progress, first becoming available after beating the World Evil boss (being locked behind the Tavernkeep NPC that only spawns after you kill the EoW/BoC) and getting upgraded (in terms of difficulty and the enemies you'll have to fight) twice in Hardmode: once after beating a Mechanical Boss and then after Golem. There are 3 (mini)bosses, with 2 first appearing in a respective tier and later both appearing in the final one with the remaining boss. They're the Dark Mage (a book-riding necromancer first appearing in the final wave of Tier 1 and later in Tier 3), Ogre (a giant club-wielding cyclops, spawning in the final wave in Tier 2 and later in Tier 3), and Betsy (a dragon that spawns on the final wave of Tier 3).

Also notably the only event that forces you to build an arena, since a relatively large, flat area is required to summon the event by using an Eternia Crystal on its Stand, and also blocks building and breaking blocks as long as it is active. You can get some gear out of it, either from boss drops or buying it from the Tavernkeep using Defender Medals you can collect for beating waves. You get 5 Medals for free from said Tavernkeep at the start, so make sure you grab a basic tower from him to make your life easier.