Epigraphs strengthen the squad assigned to their plan. Equipping, promoting and consuming them for Raven Evolution are different decisions. Start with the linked articles below; purple and gold faction-specific effects apply only to qualifying heroes.
The Raven Nest and the Epigraph Workshop as they appear in the Sanctuary.
Step by step
Build the Epigraph Workshop when it becomes available.
Upgrade it to level 10 asap.
Click on the Epigraph Workshop and then click on 'Craft' and it will open the workshop as shown below:
Tapping Craft in the Epigraph Workshop opens this screen — pick an epigraph from the UR/SSR list to see its recipe and craft it.The Bag tab shows every epigraph already in your inventory, sorted by quality, with faction filters along the bottom.
But wait. Before you start crafting your Epigraphs, you must understand epigraphs and Raven Evolve.
Detailed guides
Read the Detailed Guides in order, to understand what to do with the epigraphs.