How do I make the Demolitionist NPC happy in Terraria?

To make the Demolitionist NPC happy in Terraria, you need to understand the NPC happiness system, which was introduced in the 1.4 update. This system allows NPCs to have preferences for specific biomes and neighbors, which directly affects their happiness. A happy NPC will offer discounts on their items and, in some cases, sell unique items that are otherwise unavailable. The Demolitionist is a unique NPC who sells explosives and related items, making him valuable for mining and combat. To maximize his happiness, you need to place him in a biome he likes and pair him with neighbors he prefers.

The Demolitionist prefers the Underground or Cavern biomes, as these are the environments where he feels most at home. If you place him in these biomes, his happiness will increase. Additionally, he likes certain NPCs as neighbors. The Demolitionist enjoys living near the Tavernkeep and the Mechanic. The Tavernkeep is a special NPC who sells items related to the Old One's Army event, and the Mechanic sells wiring and mechanical items. Placing the Demolitionist near these NPCs in the Underground or Cavern biome will significantly boost his happiness.

To set this up, you need to create suitable housing in the Underground or Cavern biome. Start by digging down until you reach the Underground layer, which begins just below the surface. You can identify this layer by the change in background music and the appearance of stone blocks. Once you are in the Underground or Cavern biome, clear out a space for housing. Each NPC requires a room that is at least 6 blocks wide and 10 blocks tall, with walls, a light source, a table, and a chair. You can use platforms for the floor or ceiling, but the room must be enclosed. Place the Demolitionist, Tavernkeep, and Mechanic in adjacent rooms to ensure they are neighbors.

One common mistake is placing the Demolitionist in the wrong biome or with the wrong neighbors. For example, if you place him in the Forest biome or near NPCs he dislikes, such as the Arms Dealer, his happiness will decrease. This will result in higher prices for his items and no access to unique items. Another mistake is not providing proper housing. If the rooms are too small or lack essential furniture, the NPCs will not move in, and you will not be able to take advantage of the happiness system.

Advanced techniques involve optimizing the placement of multiple NPCs to maximize happiness across your town. For example, you can create a multi-level housing complex in the Underground biome, with the Demolitionist, Tavernkeep, and Mechanic on one level and other NPCs on different levels. This allows you to keep the Demolitionist happy while also managing the happiness of other NPCs. Additionally, you can use teleporters to quickly move between different parts of your town, making it easier to manage NPCs and access their items.

Resource requirements for this setup include stone blocks, wood, torches, and furniture. You will need to gather these materials by mining and chopping down trees. Preparation involves creating a safe environment in the Underground biome, as it can be dangerous due to enemies like bats and skeletons. Equip yourself with weapons and armor suitable for your current progression to defend against these threats. If you are playing as a ranged class, consider using a bow or gun, while melee players should use a sword or spear. Magic users can rely on spells like the Water Bolt or Demon Scythe.

In summary, to make the Demolitionist happy, place him in the Underground or Cavern biome and ensure he is near the Tavernkeep and Mechanic. Provide proper housing with walls, light, a table, and a chair. Avoid placing him in the wrong biome or with disliked NPCs. Use advanced techniques like multi-level housing and teleporters to optimize your town. Gather the necessary resources and prepare for combat in the Underground biome. By following these steps, you can maximize the Demolitionist's happiness and take full advantage of his discounts and unique items.