Creativerse tooltips roofs and slopes 2017-04-28 15-06-49-505
Creativerse crafting recipes roofs R41,5 13
Creativerse unlocks R41,5 2017-05-17 14-44-19-301 decor blocks, roofs, stairs
Creativerse Roofs R23 3335
Creativerse Roofs R23 3337
Creativerse R41,5 processing corners for roofs 513
Creativerse R41,5 Roofs with inner and outer corners 47

The Obsidian Roof is a dark blue, nearly black slanted building-block that you can use as a roof-tile or for other purposes (it can be rotated).

It can be crafted in your Crafting Menu (default key "Q"), but only after the crafting-recipe has been unlocked by

Crafting/taking blocks of Obsidian Roof is one of the unlocking requirements of the recipe for Iron Roofs.

To craft 8 (blocks of) Obsidian Roofs at a time, you'll need (as of R43 in May 2017):

Since R42 in May 2017, inner and outer corners blocks can be created for Obsidian Roofs too by putting them into a Processor. No crafting recipes are required for this.