Obsidian Stairs are building blocks cut into an L-shape colored dark-blue with cracks.
Usually placed as stairs they will smooth the player-character's movement up and down gradients so no jumping is necessary. They can be placed as projections of walls or for other purposes too when being rotated by pressing and holding R (as the default key) while moving the mouse.
Obsidian Stairs can be crafted in your Crafting Menu (default key "q"), but only after the according crafting recipe has been unlocked by
- creating Obsidian Slabs by putting Obsidian bars into a Processor. Obsidian Ore can be extracted from Nodes found on the Fossil layer accessible through shallow caves, or in rocky Mountains; or Obsidian Ore can also be found in Iron Treasure Chests or Diamond Treasure Chests
- crafting or taking Stone Stairs (unlocked after crafting/taking Wood Stairs)
Crafting or taking Obsidian Stairs is one of the unlocking requirements for the crafting recipe of Iron Stairs.
To craft 4 (blocks of) Obsidian Stairs at a time, you'll need
- 2x Melted Wax made of Beeswax in a Forge or looted from Wood Treasure Chests or Stone Treasure Chests
- 2 Obsidian Slabs made of Obsidian (bars) in a Processor
- 1 Stone Rod made of Stone, Limestone or Bedrock in a Processor