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

Creating a base in Terraria that is resistant to the Old One's Army events requires careful planning, strategic building, and understanding the mechanics of the event. The Old One's Army is a wave-based event where enemies spawn from portals and attempt to destroy the Eternia Crystal, which you must protect. To build a base that can withstand this event, you need to focus on defense, mobility, and efficient resource management.

First, let's discuss the mechanics of the Old One's Army event. The event has multiple tiers, depending on your progression in the game. Tier 1 occurs pre-Hardmode, Tier 2 in early Hardmode, and Tier 3 after defeating Plantera. Each tier introduces stronger enemies and more challenging waves. The event takes place around the Eternia Crystal Stand, which you place on a flat surface. Enemies will spawn from portals on either side of the stand and move toward the crystal. Your goal is to prevent them from reaching and destroying the crystal.

To build a base resistant to the Old One's Army, start by selecting a suitable location. Choose a flat area in the surface layer, preferably near your main base for easy access. Clear out any obstacles and ensure there is enough space for your defenses. The area should be at least 100 blocks wide to accommodate the event's mechanics.

Next, construct a platform system. Build multiple layers of platforms above the ground to create a multi-level arena. This allows you to move vertically and attack enemies from different angles. Space the platforms about 10 blocks apart to give yourself room to maneuver. Use solid blocks for the platforms to prevent enemies from passing through.

Now, focus on defense. Place walls or barriers on either side of the Eternia Crystal Stand to slow down enemy movement. Use blocks like Stone Slabs or Lihzahrd Bricks, which have high durability. You can also add traps such as Dart Traps, Super Dart Traps, or Flame Traps along the pathways to damage enemies as they approach. Wire these traps to a timer or pressure plate for automatic activation.

Incorporate NPCs into your base for additional support. Certain NPCs, like the Tavernkeep, provide unique items and buffs that can aid in the event. Place their houses nearby but ensure they are protected from enemy attacks. NPCs can also distract enemies, giving you more time to deal with them.

For combat strategies, choose a class that suits your playstyle. Melee classes can use high-defense armor and weapons like the Terra Blade or Solar Eruption to deal with close-range enemies. Ranged classes benefit from weapons like the Megashark or Tsunami, which can attack from a distance. Magic users can utilize spells like the Razorblade Typhoon or Last Prism for high damage output. Summoners can summon minions to assist in combat, reducing the number of enemies you need to handle directly.

Resource management is crucial. Stock up on healing potions, mana potions, and buffs like Ironskin, Regeneration, and Swiftness. Craft or purchase these items before the event to ensure you are well-prepared. Additionally, gather materials for building and traps, such as wire, pressure plates, and blocks.

Common mistakes to avoid include underestimating the event's difficulty, especially in higher tiers. Ensure your base is well-fortified and your character is adequately equipped. Avoid placing the Eternia Crystal Stand too close to the edges of your arena, as this can make it harder to defend. Also, do not rely solely on traps; active combat is necessary to succeed.

Advanced techniques include optimizing your arena with teleporters. Place teleporters at strategic points to quickly move between levels or escape dangerous situations. You can also use actuators to create temporary barriers or pathways, allowing you to control enemy movement more effectively.

In summary, building a base resistant to the Old One's Army requires a combination of strategic planning, defensive structures, and effective combat strategies. By creating a multi-level arena, incorporating traps and NPCs, and preparing your character with the right equipment and resources, you can successfully defend the Eternia Crystal and emerge victorious in the event.