In the last part we setup a simple teleport network to efficiently travel between your base, the pillar centers, and the dungeon. Today we setup the actual killing chambers. The materials you will need are four (or five) teleporters, the same amount of heart statues and switches and pressure plates, copious amounts of wire and building blocks, an ice wand for scaffolding, some hammer, and a mount for transit. You can also borrow spears and spike balls from the temple area or elsewhere. For usage, you will need some summon weapon for combat (or something that can attack through walls), a cross necklace, and 25 defense. Healing potions are also recommended.
The construction of the killing system is rather simple. Each station (excluding your base) has what we call an Oscillator, a hoik powered loop that rapidly inflicts fall damage to maintain invincibility frames. The design used here requires a cross necklace so that your immunity frames last the period of the cycle, however designs exist (that involve one more teleporter per station) that roughly halve the period of the cycle. The footprint of the oscillator is a 5x33 rectangle (possibly a bit higher) and everything is contained inside or on this shape. The design can be flipped horizontally, however we assume a Right-handed design, where the oscillation happens in a counterclockwise manner.
From each teleporter station, place one block to the right of the teleporter and build a wall a few blocks up to serve as a backboard. Then, build a 5-block long floor somewhere. I usually build this on top of the backboard, and centered on the teleporter. Place a teleporter in the center of this floor, and use two blocks to make a 5x2 rectangle. Now, from there, on the right hand side, we need to build nine spikes that are formed by placing down one full block at the rightmost edge of the 5x33 rectangle, and then a single slope whose hypotenuse faces up and to the left, attached to the left of it. The first spike begins three blocks above the teleporter (so two air blocks separate it and the teleporter), and subsequent spikes three blocks above the preceding one. Create a 10th spike two blocks above the 9th one (so one block of separation), and then a 5 wide roof two blocks above the 10th spike, aligned with the floor down below. Finally, place a heart statue somewhere on this roof. You may also enclose this heart statue to prevent the hearts from escaping.
The spikes on the right side serve to transport you up, and then to the left. We now create a similar set of 10 spikes on the left: the first one three blocks down from the roof, and then each subsequent one up to nine placed three blocks down from the preceding one. The tenth spike, naturally, goes two blocks below the 9th one, and the teleporter should then be two blocks down from the aformentioned 10th spike. And analogous to the slopes from the right side, these ones are composed of a full block and a slope facing down and to the right. Place a pressure plate on the center of the teleporter, and wire it up to the heart statue. Lastly, wire the teleporter to the original teleporter down at the station, with a lever to take you into the mechanism.
To use the system, first equip the cross necklace and 25 defense. Then, stand on the station teleporter, and walk into the backboard wall. And finally, flick the lever to start the contraption. There should be freecam mods like Hero's mod to reduce the camera shaking. Either way, you can then start summoning minions, attacking, whatever through the safety of your system. Once the pillar is gone, use the Rod of Discord (or a recall potion) to escape and collect the drops from nearby the station. Happy farming!