NOTE: This guide applies to PC v.1.1.2, and may not be applicable to other platforms or later versions. Hey, Tunnel King here to share something that I've been using and improving over a period of time and several worlds: a grinder mechanism to deal with Blood Moons (pre-hardmode) and Goblin Army invasions (whenever). This is not beginner stuff; by the time you can get the materials and tools to build something like this, you've likely encountered several Blood Moons and a few Goblin invasions, and learned more conventional ways of defeating them, and that's a good thing. Not to mention, have defeated Skeletron and rescued the Mechanic. Building something like this is completely optional to progressing in the game. But after playing a world for a while, I find that these invasions become rather tedious. So I whipped up a very simple dart-trap defense, mainly for the Goblin invasions. This isn't an original idea at all, but I've tweaked my own design to make it more effective and more lucrative. So without further ado, here it is. The overall design is a matter of personal preference, but I'll touch on a few things that I think are important to consider. Material: You can use any blocks you want to build this thing. I used scavenged Dungeon bricks, with an eye to converting this later for Hardmode. Two dart traps, one for each side, is ample (having multiple traps shooting off the same timer will not increase damage to enemies). The Bunny statue at the left, when activated by its own timer, will spawn Corrupt Bunnies during a blood moon and significantly increase the amount of loot you can get. If you don't have a Bunny statue, don't let that stop you, you can always add it in later. I use 3-second timers for both the dart traps and the Bunny statue, due to cool-down issues. If you're new to wiring, the timers don't need switches, just right-click on them to toggle them, the floor switch you see for the dart traps is completely optional. Location: I built this at (or very near) the original spawn point (center of the map). This is where the Goblin Army will converge during an invasion, no matter which direction they approach from. I also like to build this some distance away from my NPC base, but close enough* to get to in a timely fashion. This way, the NPCs are safe from the battle, and you can get in position early in the invasion. * In this particular case, my base/spawn is far away at the Dungeon, and I use the Portal (tConfig) mod to warp to my grinder (Portal not shown). Kill Zone: I build my grinder either in a natural depression, or I build up the surface at the ends of the two runways to make it be in a depression. This concentrates the kills (and thus, the dropped loot) to the areas above the runways. So, as the dart traps are doing the killing, you can run back and forth in the runways and collect the loot in safety. Notice that the kill zone doesn't have to be very wide; the enemies will come to you. (In my picture, I have grass blocks and trees to give the illusion of camouflage, so I have to 'jump' a bit to get the drops, I could have left them out and not have to jump - your choice.) Surroundings: You want to make sure to fill in any underground cavities near your grinder, and not have other passageways nearby that the mobs can spawn in. This is especially true for the Goblin Sorcerer dudes; they can spawn and attack from quite a distance away. You want the mobs to only approach from left or right at the surface. The Deck: The spot where I'm standing in the picture. The way it extends over the central area makes a good trap for Demon Eyes; when you stand between the dart traps they seem to be attracted there in large numbers and die quickly. The height is low enough to keep the enemies from jumping and not getting hit by the darts, and the barriers at the end keep them from jumping onto the deck. This is also where I fight off the Goblin Sorcerers that spawn there or on the (completely optional) roof; a Vilethorn is a perfect weapon for this. Miscellaneous: I put a few chests around in the protected area. I dump Spiky Balls in one (and occasionally toss out a few in the kill zone for extra killing pleasure), and use another as a dump box (in case I was off gathering material somewhere and my inventory is too full to pick up all the loot I'm about to get). I also keep a stack of Battle Potions and an extra Vilethorn in one chest. During Blood Moons, I use one Battle Potion (they last 7 minutes, I try to wait until about the 9:00 mark to use it) and hold that Water Candle you see just below me to the right to significantly increase the enemy spawn rate. So, what do I get for all this? A lot of loot (coins + drops) for very little effort. With the Goblin Invasion, it just makes the battle cleaner and shorter (usually done by 10:00 am in my experience). With the Blood Moons, using the Battle potions and Water Candle brings hoards of zombies straight into the kill zone, dropping Shackles (3+ silver each) and the occasional Top Hat from The Groom (20 silver each). Add in the Bunny statue, and you get Bunny Hoods (40 silver each). Demon Eyes drop 10-20 Lenses, including rare Black Lenses (10 silver each). This is all on top of the coins dropped. Note that this is not an AFK opportunity; you'll quickly reach the dropped item limit and start to lose stuff. Run around and pick it up once in a while to maximize your gain. So, 2+ gold per Blood Moon (without bunny), 10-12+ gold with bunny, plus more for selling the extra drops. Not too shabby. What about Hardmode? Dart traps do little damage to Hardmode mobs, but this basic design could easily be adapted to use lava traps over the runways instead (I'll leave that as an exercise for the reader). Also, Wraithes will have to be dealt with separately; a good polearm or sword should do the trick. If you build the structure out of Dungeon brick, then the most damage Clowns can do is to knock off a few wall tiles, if the lava doesn't kill them first. I could do better than this. Sure you could (or I could). You could add more bunny statues, or wire stuff up to work with shorter cool-down and 1-sec timers, you could toss in a goldfish farm,... I only claim that this is a Pretty Good grinder, not optimal. At some point there is a global spawn limit that will cap the number of enemies at one time, but you could probably tweak it up to 15+ gold on a good Blood Moon, or perhaps even higher. If you have interesting grinder designs of your own, feel free to post them here, and thanks for reading. BONUS PICS - LIVE ACTION!! (Move your mouse to reveal the content) BONUS PICS - LIVE ACTION!! (open) BONUS PICS - LIVE ACTION!! (close) Here's a Blood Moon in progress. Note Battle Potion in effect, Water Candle in hand. The Groom is approaching on the right, and you can just see the ears of a Bunny Hood peeking up near the left dart trap. And here's the loot obtained on this night. Pretty good haul.