Old One's Army
Defend the Eternia Crystal as portals bleed forth an ancient, alien horde
The Old One's Army is a unique Dungeon Defenders 2 crossover event that can be triggered by placing an Eternia Crystal on an Eternia Crystal Stand . Waves of enemies begin spawning from portals on both sides of the crystal , seeking to destroy it. The objective is to protect the Eternia Crystal until all waves are cleared – if the crystal is destroyed, the event automatically ends. There are three different versions, or "tiers", of the event: Clearing later waves rewards the player with Defender Medals , a unique currency that can be used to purchase special weapons , armor , and the Defender's Forge from the Tavernkeep NPC . This gear is specifically suited for the event, due to its exceptional level of difficulty, and stronger equipment is unlocked with each progressed tier. Not only are its enemies extraordinarily resistant, but it also employs numerous anti-cheat/exploit mechanisms , such as preventing the player from placing or removing blocks or liquids for the event's duration. - 1 Summoning 1.1 Terrain requirements - 2 Waves - 3 Defender Medals and sentries - 4 Drops - 5 Contents - 6 Anti-cheat mechanisms 6.1 Oversights - 7 Wave chart - 8 Equipment chart - 9 Status messages - 10 Notes - 11 Achievements - 12 Tips - 13 Trivia - 14 See also - 15 History - 16 References - After defeating the Eater of Worlds or Brain of Cthulhu , the Old One's Army is unlocked in its first tier with an initial maximum of five waves. - After defeating any mechanical boss , the event receives a substantial increase in difficulty in its second tier and gains two more waves, totaling a maximum of seven. - After defeating Golem , the event reaches its third, final tier of difficulty, with the full range of enemies and mini-bosses present in some way during the seven waves.
Lore & Background
The conflict evolves with the world's own history. Before the mechanical horrors are laid low, only the first tier awakens, offering a glimpse of the threat through the cunning Dark Mages. As the land scars from mechanical beasts, the army grows stronger, introducing the hulking Ogres in the second tier. Yet, it is only after the Golem's defeat that the full fury of the third tier descends. Here, the portals widen to unleash all enemies at once, culminating in a battle against Betsy herself, whose wings blot out the sky and whose breath melts stone. Victory grants not just survival, but Defender Medals, currency forged from the chaos to craft weapons capable of holding back the void.
In Their Own Story
As the waves swell, the air fills with the screech of flying horrors and the heavy thud of Ogre footsteps. You watch your sentries, summoned by the etherial energy you gathered from fallen foes, stand firm against the onslaught. The countdown timer blinks above the crystal, a ticking heart in the chaos. When the final wave arrives, Betsy emerges, a dragon of fire and scale, her roar shaking the very tiles beneath your boots. You dodge her breath, striking true until the beast falls, and the portals seal shut. Silence returns, broken only by the soft chime of Defender Medals spilling from the defeated, ready to fuel your next defense.
Reader's Guide
To summon the Old One's Army, you must first defeat Eater of Worlds or Brain of Cthulhu to find the Unconscious Man, who becomes the Tavernkeep. Purchase an Eternia Crystal Stand and Crystal, then ensure a flat arena: 60 tiles of clear space on each side of the stand (121 total) and 10 vertical tiles clearance. Floors must be solid with no holes wider than one block.
The event features three tiers based on progression. Tier 1 (pre-Mechanical Bosses) has five waves ending with Dark Mages. Tier 2 (post-Mechanical Bosses) adds two waves and Ogres as the final boss. Tier 3 (post-Golem) unleashes all enemies, including Betsy in the final wave. Enemies spawn from portals on both sides.
Protect the crystal at all costs; if it breaks, the event ends. Use sentry summons fueled by Etherian Mana dropped by enemies to defend multiple lanes simultaneously. Skip wave countdowns by activating the stand for faster pacing. Rewards include Defender Medals (5 for Tier 1, 25 for Tier 2, 100+ for Tier 3) used at the Tavernkeep for powerful sentry gear and weapons.
Did You Know?
- The Eternia Crystal cannot be placed if the terrain does not meet strict clearance requirements of 60 tiles per side.
- In Expert Mode, Betsy's Treasure Bag drops an additional 30–49 Defender Medals upon defeat in Tier 3.
- Players can skip the 30-second wave countdown by pressing Open/Activate on the Eternia Crystal Stand.
- Etherian Mana collected during the event vanishes completely once the battle concludes, regardless of inventory storage.