Warp pipes should have underground rooms from a randomly selected list, and occasionally lead to a short linear dungeon with warp pipe on the far side. Shouldn't be impossible to do with jigsaw blocks.



There should also be a ground structure which places a coin heaven above it and contains a ? block with a vine.



To make this, make the ? block drop an item with a custom NBT tag, and when an item entity with that NBT is detected, it sets the block its in to a solid brick (so the vine has an anchor) and then summons a Marker entity and kills itself. This vine_tip Marker is teleported upward each tick, and if it is in an nonsolid block (use a block tag so vines can grow through air, cave_air, torches, and some other blocks) it replaces the block its in with warped vines (since they grow upward). When it hits a solid block (don't put void_air in the #vine_replaces tag or whatever so you can use a void_air in the coin heaven structure to stop the vine automatically at that height) or grows to some large total height (count this with a scoreboard) kill the Marker so the vine stops growing.