Old One's Army
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The Old One's Army is a unique Dungeon Defenders 2 crossover event that can be triggered by placing an Eternia Crystal on the 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 it until all waves are cleared – if the crystal is destroyed, the event ends.
There are three different versions of the event: It first becomes available after defeating the Eater of Worlds/Brain of Cthulhu (first tier), receives a substantial increase in difficulty after defeating any mechanical boss (second tier), and upgrades to its final version once Golem has been defeated (third tier).
Clearing later waves rewards the player with Defender Medals, a unique currency that can be used to purchase special weapons and armor from the Tavernkeep NPC. This gear is specifically suited for the event, due to its exceptional level of difficulty. Not only are its enemies extraordinarily resistant, it also employs numerous anti-cheat/exploit mechanisms, such as preventing the player from placing or removing blocks or liquids for its duration.
To initiate the Old One's Army event, an Eternia Crystal Stand must be placed first. An Eternia Crystal must then be placed on it by pressing the ⚷ Open / Activate key on the stand. Both the crystal and its stand are purchased from the Tavernkeep NPC for coins. The Tavernkeep can be found randomly in a world after the Eater of Worlds or the Brain of Cthulhu has been defeated.
Summoning this event has some unique requirements for the terrain around the summon area. If they are not fulfilled, the Eternia Crystal cannot be placed successfully, and a status message appears informing the player that the surface is inadequate.
- A minimum clearing of 61 tiles horizontally is required on each side of the Eternia Crystal Stand, measured from the center of the stand (a 123-tile clearing in total, with the stand at the center tile). The enemy portals will spawn further away if given the space, however: up to 120 tiles away from the center of the stand on each side.
- A minimum clearing of 10 tiles vertically is required (i.e., between the "floor" and the "ceiling", if there is one).
- Additionally, tiles above the floor may not be immediately next to the Eternia Crystal Stand.
- The floor may not have holes wider than 1 block.
The player can build up to a height of three tiles before blocks are considered obstructing the necessary space. Platforms and inactive blocks do not count as part of a flat floor, and will count against the three-tile height allowance; but floor blocks with Actuators on them that are solid when the crystal is placed will count as flat, and can be successfully actuated after the event has started. In addition, closed trap doors are considered flat, and can be successfully opened and/or reclosed after the event has started.
The event consists of a set number of waves, with each wave becoming progressively more difficult (see wave chart). At the end of each wave, there is a 30-second countdown to the next wave, signified by a timer appearing over the Eternia Crystal.
The event comes in three possible tiers, depending on game progression when the event is triggered:
- Tier 1 consists of five waves, with one or more Dark Mages serving as mini-bosses in the final wave. Tier 1 is triggered when the event is summoned before any mechanical bosses have been defeated. The final wave will only end when a Dark Mage is killed; however, note that a single kill does not give enough points to instantly end it unless the wave is mostly already finished. Completing Tier 1 awards 5 Defender Medals in total.
- Tier 2 consists of seven waves, with one or more Ogres serving as mini-bosses in the final wave. Dark Mages will not appear in this tier. Tier 2 is triggered when the event is summoned in a Hardmode world after at least one mechanical boss has been defeated. The final wave only ends upon the death of an Ogre. Completing Tier 2 awards 25 Defender Medals in total.
- Tier 3 consists of seven waves, with the boss Betsy spawning in the final wave. The Dark Mage and Ogre will also spawn during the previous three waves. Tier 3 is triggered when the event is summoned after Golem has been defeated. The final wave ends when Betsy is defeated. Completing Tier 3 awards 100 Defender Medals in total. In Expert Mode worlds, an additional bonus of 30-49 Defender Medals is dropped by Betsy's Treasure Bag. Furthermore, in Master Mode worlds, the boss relics will only drop during this wave.
In addition to the difference in bosses, the common event enemies also differ between Tiers, with stronger statistics and a more menacing appearance in higher tiers.
Pressing ⚷ Open / Activate on the Eternia Crystal Stand during the cooldown between waves will allow the player to skip the delay and immediately start the next wave. The Eternia Crystal Stand and the completion message of the first wave also indicate this fact.
Defender Medals and sentries
The completion of each wave, beginning with the third, awards the player Defender Medals, a special currency used to purchase items from the Tavernkeep NPC that can help players defeat future Old One's Armies. Among them are special sentry summon weapons, which are fueled by Etherian Mana, a resource that drops only during this event. Etherian Mana allows multiple sentry minions to remain placed simultaneously and permanently until the event is over, with more Etherian Mana allowing more sentries to be placed. All Etherian Mana disappears once the event is over, whether uncollected or within the player's inventory.
At the beginning of the event, the player will receive 10 Etherian Mana, allowing them to place one sentry. Note that sentries not obtained from the Tavernkeep (such as the Queen Spider Staff) do not and cannot use Etherian Mana, but can be summoned separately.
Each sentry type available from the Tavernkeep (Flameburst, Explosive Trap, Lightning Aura, Ballista) comes in three different tiers: Rod, Cane, and Staff, with the Staff being the most expensive and the most powerful.
Once the event is completed successfully in a world, the weapons can then be used outside the event with normal summoning rules.
Several enemies also drop pets, vanity items, and powerful weapons and accessories. All enemy banners dropped during this event are functional, although they provide the player a much weaker buff compared to that of other enemy banners.
Enemies will not drop biome-specific drops, such as Biome Keys, or coins, even when wearing the Lucky Coin or its derivatives. They also do not drop Presents during Christmas, nor Goodie Bags during Halloween.
- The Creative Shock debuff prevents placing or mining blocks during the event. It also prevents using Buckets to spill or collect any liquids.
- All blocks: Blocks cannot be used to completely prevent event enemies from advancing. Old One's Army enemies are able to go to enter a "ghostly" state where they can move through blocks. They initially spawn in this state, then re-enter it whenever there is no clear path between them and the player. For example, if the player enters a tunnel below the arena, enemies will fall through the blocks to enter the tunnel.
- Teleporter: Event enemies are not affected by Teleporters, rendering them useless for the event. However, players are still able to use them.
- Lava: Event enemies take no damage from lava, rendering it useless for the event.
- Water, Honey, Honey Blocks: These will not slow down the enemies.
- Traps: While traps will damage event enemies normally, they are less efficient than sentries; Traps can additionally make sentries less effective, since trap attacks cause invincibility frames in the enemies they hit, while sentries do not. Traps may still be useful in areas out of the reach of sentries.
Things that are still possible:
- Actuators can be used to transform the arena after the event has started. Keep in mind that walls can result in the enemies simply moving through.
- Ice Rod can place temporary ice blocks.
- Dirt Rod can be used to move Dirt Blocks in the area.
- Weapons and tools that create placed blocks are usable and will produce blocks. However, these blocks cannot be removed with tools until the event is over.
- Proximity Mine Launcher and explosives can destroy blocks that are not explosion-proof.
- Conveyor Belts can be used to move Etherian Mana towards the player. Note that they do not move enemies, only the player, as usual.
- Etherian Mana can be placed in a storage item (e.g. a Chest or Piggy Bank) left unopened between events, allowing it to be reused for future events.
- It is possible to open a storage item with Autopause enabled to stop it from disappearing in between events.
- Minecart Tracks are allowed in the arena, allowing the player to use Minecarts to run over enemies.
|Pre-Mechanical Boss (T1)||After Killing One Mechanical Boss (T2)||Post-Golem (T3)|
|Enemy||Wave 1||Wave 2||Wave 3||Wave 4||Wave 5||Wave 6||Wave 7|
|Etherian Goblin Bomber|
|Etherian Javelin Thrower|
|Dark Mage + Old One's Skeleton|
|Etherian Lightning Bug|
|Etherian Mana Reward||20||20||20||20||20||20||20||20||20||30||20||20||40||20||30||30||30||30||30|
|Defender Medal Reward||1||1||1||1||3||3||3||11||6||25||15||60|
The Old One's Army event brings associated equipment. The armor and sentry weapons are available from the Tavernkeep in exchange for Defender Medals, while other weapons and accessories are dropped by event enemies. Though all of the equipment is coordinated with other equipment of the same class, the only specific benefit from this coordination is the buffs granted to each sentry by the corresponding armor set bonus; neither the weapons nor the accessories are involved in any additional unique bonuses, and so can be used with any other armor or exchanged for any other weapon at the player's preference.
|Class||Sentries||Tier 2 Armor||Tier 3 Armor||Tier 2 Weapon||Tier 3 Weapon||Accessory|
||Apprentice||Dark Artist||Tome of Infinite Wisdom||Betsy's Wrath||Apprentice's Scarf|
||Huntress||Red Riding||Phantom Phoenix||Aerial Bane||Huntress's Buckler|
||Monk||Shinobi Infiltrator||Sleepy Octopod /Ghastly Glaive||Sky Dragon's Fury||Monk's Belt|
||Squire||Valhalla Knight||Brand of the Inferno||Flying Dragon||Squire's Shield|
All unique status messages associated with the Old One's Army event are listed below.
When the Eternia Crystal is destroyed:
- "The old one's army proves victorious..."
When the first wave is completed:
- "Wave Complete! Interact with the Crystal to rush next wave!"
When a wave is completed:
- "Wave Complete!"
When the Eternia Crystal Stand is placed at an inadequate location:
- "The eternia crystal rejects this area and pops away instantly, the Tavernkeep mentioned it should rest in a large flat open area..."
- The Eternia Crystal regenerates its health very slowly when not taking damage.
- The Eternia Crystal has 2× as much health in Expert Mode and 3× as much health in Master Mode.
- Bringing a mechanical boss's summoning item to a pre-Hardmode world and vanquishing one will still only produce Tier 1 of the invasion.
- Traps like Spiky Ball Traps or Super Dart Traps can do a small amount of damage to the Eternia Crystal.
- At the start of the 7th wave at T3, Betsy will spawn off-screen on the ground instead of from the Mysterious Portals.
- The event is considered cleared once the final boss of each Tier is defeated, regardless of how many enemies are left at that point. The "cleared" status is indicated by white light surrounding the Crystal, as well as a change in music, by which point the event is considered won even if enemies then proceed to touch the Crystal or the player dies. The event can even be won posthumously, if the remaining sentries finish off the last boss.
- The four sentry-boosting accessories have identical effects and do not stack with each other. They differ only in appearance, each matching one of the Tier 2 armor sets.
- If the player kills the boss while the crystal is broken, the game will still count it as a failure and the player will not get Defender Medals nor the victory message. However, bosses defeated this way will still drop their unique loots.
- Because of the Creative Shock debuff, any building work to prepare the arena must be completed before. It is not possible to place or remove blocks or furniture while the event is happening, not even between waves.
- During the event, players can combine two different kinds of sentry with different limits:
- The sentries (Queen Spider Staff, the Staff of the Frost Hydra, the Rainbow Crystal Staff, and the Lunar Portal Staff) work as normal: The player pays a modest amount of mana, and each last the usual 10 minutes. By default the player can only summon one at once, but Tavernkeep armor and/or Ogre drops will let them summon more.
- During the event, the Tavernkeep sentries are not (and cannot be) summoned with regular mana. Instead they cost 10 points of the event's Etherian Mana. The Etherian Mana supply is the only limit to how many the player can summon, and they will last until the event ends. (Outside the event they work like any other sentry.)
- In general, players will likely struggle to finish the Old One's Army without a Tavernkeep sentry for the tier; for later tiers having a set of Tavernkeep armor will also help. The player gets a Tier 1 sentry for free; saving up
150000*15 will let them buy a Tier 2 sentry before facing the Tier 2 army. If they can save up a full 450000*45 , they will also be able to buy Tier 2 armor up front. During Tier 2, they should focus on collecting at least 600000*60 for a Tier 3 sentry – another 1500000*150 in addition will let them get the armor as well. Note that both the sentries and the armor are also quite useful for regular gameplay.
- If the player is in a Hardmode, non-Expert world but has yet to defeat a mechanical boss, they can easily farm the event with a Blessed Apple or Ancient Horn mount. Simply run back and forth. The damage the mounts do while charging will one-hit kill all enemies besides the Dark Mage.
- The Eternia Crystal slowly develops cracks as it gets more damaged.
- In the Bestiary, some of the enemies will appear as their Tier 3 variant, even before reaching the tier.
- In the game files, an unused NPC called DD2AttackerTest can be found. It looks identical to the Angry Tumbler enemy.
- Old Ones at the Dungeon Defenders 2 Wiki
- Desktop 1.4.4:
- Etherian Lightning Bugs now spawn in OOA Tier 3 Wave 6 instead of Wyverns.
- The Eternia Crystal now has 2× as much health on Expert and 3× as much health on Master.
- Desktop 184.108.40.206: Fixed situations where the enemies would spawn invisible in multiplayer if they were too far from the player.
- Desktop 220.127.116.11: Fixed portals not emitting light.
- Desktop 18.104.22.168:
- Desktop 1.3.4: Introduced.
- Console 1.17: Introduced.
- Switch 1.0.1096.2: Introduced.
- Mobile 22.214.171.124.0: Introduced.