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.
此事件有三种难度版本： It first becomes available after defeating the 世界吞噬怪/克苏鲁之脑 (first tier), receives a substantial increase in difficulty after defeating any 机械 Boss (second tier), and upgrades to its final version once 石巨人 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 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 ⚷ 打开/激活 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.
- 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).
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.
此事件由一定数量的波数组成，每一波会变得越来越困难（参见波数图表）。在每一波结束时，会有下一波的 30 秒倒计时，由出现在埃特尼亚水晶上方的计时器来表示。
- 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 one of them does not give enough points to instantly end it. 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 ends when one Ogre is defeated. The Ogre's treasure bag is unobtainable, therefore it will not drop. 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.
除了 Boss 的差异外，普通事件敌怪在不同级别中也有不同，在高级别中属性更强且外观更具威胁性。
在此事件开始时，玩家会收到 10 个天国魔力，允许他们放置一个哨兵。注意不是从酒馆老板处得到的哨兵（比如蜘蛛女王法杖）不使用也不能使用天国魔力，但可以单独召唤。
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. However, they do have the universal 1/2500 (0.04%) chance to drop a summoning item for any Mechanical bosses that have not yet been defeated.
- 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.
- 传送机: Event enemies are not affected by Teleporters, rendering them useless for the event. However, players are still able to use them.
- 熔岩: Event enemies take no damage from lava, rendering it useless for the event.
- 大炮: Cannons and Bunny Cannons deal no damage to event enemies, rendering them useless for the event.
- 机关: 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.
- 制动器 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, but this can help protect the crystal from projectiles. (these might not work)
- 土魔杖 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.
- 感应雷发射器 and Explosives can destroy blocks that are not explosion-proof.
- 传送带 can be used to move Etherian Mana towards the player. Note that they do not move enemies.
- 天国魔力 : Prior to 220.127.116.11, can be placed in a chest, where it remains for use in the next Old One's Army, as long as the chest is not opened until then. As of 18.104.22.168, this will now only work in a Piggy Bank, Void Vault or similar left unopened between events.
|机械 Boss 之前（T1）||打败了一个机械 Boss 后（T2）||石巨人后（T3）|
|Enemy||Wave 1||Wave 2||Wave 3||Wave 4||Wave 5||Wave 6||Wave 7|
|黑暗魔法师 + 撒旦骷髅|
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.
- 将机械 Boss 召唤物品带到困难模式之前的世界中并干掉一个机械 Boss 依然只会产生一级的入侵。
- 一旦每个级别的最终 Boss 被干掉，该事件将被即视为已通过，无论在此时还留有多少敌怪。“已通过”状态由环绕水晶的白光和音乐的变化来表示，在这个时刻此事件即视为胜利，即使敌怪随后开始接触水晶或者玩家死亡。如果遗留的哨兵干掉了最终 Boss，此事件甚至可以在死后获胜。
- 四种哨兵强化配饰有着相同的效果并且互相之间不叠加。它们仅有外观不同，各自和一套 2 级盔甲套装相配。
- If the player kills the boss while the crystal is broken, the game will still count it as a failure and the player won't get Defender Medals nor the victory message.
- 如果你正在进行此事件的全部 3 个级别，建议在打败机械 Boss从而转移到 T2 之前先通过进行 T1 来存下 25 枚护卫奖章。这样，你就可以在尝试进行事件的 T2 版本之前购买一件 T2 哨兵召唤武器。只用 T1 装备来尝试打败 T2 事件会让你处于显著劣势。出于同样的原因，建议在 T2 时存下足够的护卫奖章以在 T3 装备变为可用时可以购买一些。
- As the presence of water does not impact terrain requirements, an arena filled partially or completely with water can allow use of certain mounts or items to allow increased 3-dimensional mobility. Superheated Blood can be obtained as soon as lava fishing is available and should be combined with a Gills Potion for a submerged arena. Shrimpy Truffle also provides increased damage under these circumstances and can be obtained, with difficulty, during the Tier 2 timeframe. A submerged arena should be well-lit with Coral Torches and carefully placed; when located in, for example, the Jungle or Ocean biomes, Arapaima or Sharks can spawn and attack the Eternia Crystal.
- If you are in a Hardmode world but have yet to defeat a mechanical boss, you 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. (This does not work if your world is on expert mode)
- 游戏终期的策略：最大限度的召唤者，有 11 个星尘细胞法杖仆从和传奇 狂星之怒，可以波澜不惊地在事件中通过第 6 波。第 7 波需要大量躲避，但 Boss 可能会在它摧毁水晶之前就死掉。太空海豚机枪加上夜明弹或幻影弓加上夜明箭也非常有用。其他有用的游戏终期物品：终极棱镜、暗影束法杖、雪人炮、毒气瓶、彩虹猫之刃、孢子囊、大地法杖、鳞甲怪坐骑。
- 如果你使用爬藤怪法杖，它可以作为屏障。结合单个闪电光环哨兵，它可以干掉一侧的军队，一直到大约第 4 波。
- 雨云魔杖在 T1 中极其有效，因为它能秒杀黑暗魔法师外的所有敌怪。如果你将云放在传送门朝向水晶的那一侧，除了黑暗魔法师外的所有敌怪都无法通过，而玩家可以处理黑暗魔法师。但是，你需要经常更换云。
- Hoik 可以在某种程度上用于将天国魔力推向你，但只能向右推。另一个较慢的替代方案是传送带。这的用处很有限，因为两波之间的间歇计时提供了大量的时间来手工收集天国魔力。
- Hoik 可以用于埃特尼亚水晶自身，一个 Hoik 环路可以持续移动水晶，使其不易被击中。
- Due to the sheer amount of enemies, piercing ammunition, such as Jester's Arrows, can be quite useful. The Flying Knife is also very useful.
- Although the second tier is unlocked after only one mech boss has been defeated, it is not recommended to fight the army until you have beaten all of the three bosses as even adamantite or titanium armor and gear will likely not be enough to progress to the later waves.
- However, using the above strategies and/or the actuator drop strategy, It is possible and easy to defeat the second tier with weaker armor and weapons.
- During the event sentries purchased from the tavern keep behave different from normal turrets.
- The player can place more turrets than the normal turret cap
- Placed turrets last until the end of the event (rather than the usual 2 minutes)
- Turrets placed before the event vanish when the Eternia Crystal is placed
- Normal turrets can be placed up to the normal cap in addition to the ones placed with Etherian Mana
- Using Boulder Statue connected to a Timer is recommended, as it deals massive damage.
- However, this tactic should be done just above the portal with a slope going down, as boulders can severely damage both the player and the Eternia Crystal.
- In the bestiary, some of the enemies will appear as their Tier 3 variant, even before reaching the tier.
- In the files a unused enemy known as DD2 Attacker test which looks identical to the Angry Tumbler enemy.
- 《地牢守护者2（Dungeon Defenders 2）》Wiki 上的撒旦军队
- 电脑版 22.214.171.124：Fixed situations where the enemies would spawn invisible in multiplayer if they were too far from the player.
- 电脑版 126.96.36.199：Fixed portals not emitting light.
- 电脑版 188.8.131.52：
- 电脑版 1.3.4：引入。
- 主机版 1.17：引入。