How do I create a base that is safe from Old One's Army events in Terraria?

To create a base that is safe from the Old One's Army events in Terraria, you need to understand the mechanics of the event and how it interacts with your base. The Old One's Army is a wave-based event triggered by placing an Eternia Crystal Stand and an Eternia Crystal in the world. The event spawns enemies that attack in waves, with the goal of destroying the crystal. If the crystal is destroyed, the event ends in failure. To protect your base from this event, you need to ensure that the event does not interfere with your main living area or important structures.

First, you need to choose a location for the Old One's Army event that is far enough away from your main base. The event requires a flat area of at least 61 blocks wide and 23 blocks tall to function properly. This area should be clear of any obstructions, such as trees, walls, or other structures. You can create this area by using a pickaxe to clear out the terrain or by building a platform in the sky. Once you have the area prepared, place the Eternia Crystal Stand in the center of the flat area. This will be the focal point of the event, and all enemies will target the crystal.

Next, you need to build defenses around the crystal to protect it from the waves of enemies. The Old One's Army event features a variety of enemies, including ground-based and flying units, so your defenses need to account for both. One effective strategy is to create a series of barriers and traps around the crystal. You can use blocks like stone or wood to build walls that funnel enemies into specific paths, making it easier to defend against them. Place traps such as dart traps, flame traps, or spiky ball traps along these paths to deal damage to enemies as they approach the crystal. You can also use lava traps, but be careful not to place them too close to the crystal, as they can destroy it.

In addition to traps, you should also consider using sentries and other defensive structures. Sentries are stationary weapons that automatically attack enemies within their range. You can obtain sentries by completing the Old One's Army event and earning Defender Medals, which can be used to purchase sentry summoning items from the Tavernkeep NPC. Place sentries strategically around the crystal to provide additional firepower. You can also use platforms to create multiple levels of defense, allowing you to attack enemies from above or below.

Another important consideration is the placement of NPCs. NPCs can be useful in defending against the Old One's Army, as they will attack enemies that come near them. However, you need to be careful not to place NPCs too close to the crystal, as they can be killed by the waves of enemies. Instead, place NPCs in a safe area nearby, such as a house or bunker, where they can provide support without being in direct danger.

When preparing for the Old One's Army event, it is important to have the right equipment and resources. Make sure you have a good set of armor and weapons, as well as healing items like potions. The event can be challenging, especially in higher tiers, so you need to be well-prepared. You should also stock up on building materials, such as blocks, traps, and wiring, to create your defenses. If you are playing in multiplayer, coordinate with your teammates to assign roles, such as one player focusing on building defenses while others focus on combat.

One common mistake to avoid is placing the Eternia Crystal Stand too close to your main base. If the event is triggered near your base, the waves of enemies can easily overwhelm your defenses and destroy your structures. Always place the stand in a separate area, far enough away that the event does not interfere with your main base. Another mistake is not preparing enough traps and defenses. The Old One's Army event becomes progressively more difficult with each wave, so you need to have a strong defense in place to handle the later waves.

For advanced players, you can optimize your defenses by using wiring and actuators to create dynamic traps. For example, you can use actuators to create retractable walls that open and close, allowing you to control the flow of enemies. You can also use teleporters to quickly move between different areas of your defense, making it easier to respond to threats. Additionally, you can use buffs and debuffs to enhance your combat effectiveness. Items like the Sharpening Station, Ammo Box, and Bewitching Table can provide useful buffs, while debuffs like Frostburn or Poison can weaken enemies.

In summary, creating a base that is safe from the Old One's Army event requires careful planning and preparation. Choose a location far from your main base, build strong defenses around the crystal, and use traps, sentries, and NPCs to protect it. Avoid common mistakes like placing the stand too close to your base or not preparing enough defenses. With the right strategies and resources, you can successfully defend against the Old One's Army and keep your base safe.