Minecraft wiki entry for Defeating_a_bastion_remnant, associated text: Because the bastion remnant is almost completely made of blackstone, navigation can become difficult as the monochrome makes it hard to spot un-explored stairs or corridors. Marking your path (especially where you entered the bastion) with torches or brighter blocks like cobblestone can help you can see where you've already been. The ruined pathing of the bastion also means you should have a good supply of blocks to fill in the holes in the paths so you don't fall through them.