I had an idea for a new structure the other day while I was messing around copying beacon pyramids with structure blocks. What if there was a structure with a beacon inside?
This structure would be VERY rare (think woodland mansion or ocean monument rare), spawning in jungle biomes. It would consist of a large maze made of mossy cobble, with spawners of skeletons that shoot arrows of mining fatigue at certain nodes along the way so that you must be always running and you can't break the cobblestone due to mining fatigue.
In the centre of the maze would be a mossy stone brick pyramid with a maze of random rooms, some containing phantom spawners. In the middle of the pyramid there would be a room made of water with multitudes of Drowned spawners and a conduit frame with 1 block missing. You must find a chest on the far side of the room which contains a Heart of the Sea, 8 nautilus shells, and 1 Prismarine Brick block. You must put down the Conduit you crafted, disabling the spawners with its light level, and complete the Conduit frame, attacking the rest of the Drowned. Then you can go about breaking the Obsidian wall on the far side of the room. Once you break the wall you enter the treasure room - a tiny room consisting of a Tier 1 beacon with Iron below it.