Strata Devil armors cannot chip DR nor movement speed, so they're 1 potential dr behind Greek Chroma's but make up for it with their unique effect:
Each Strata Devil armor can be chipped (1/200 chance) with a 1-15% chance to trigger a unique buff when hit, which differs per class type:
-The Spirit of the Devil: Reduces magical dmg dealt to you by 30% for 2 minutes. (Plate & Fighter only)
-Devil's Desire: Reduces shooting dmg dealt to you by 30% for 2 minutes. (Scout & Wizard only)
-Body of the Devil: Reduces melee dmg dealt to you by 30% for 2 minutes. (Musketeer only)
Where to get the materials:
- Symbol of Naraka's drop in several raids (Clocktower, Crow, etc), and can be made by combining Naraka pieces in Viron.
- Devil's Dream can be gotten via alchemy in viron, ideally around a combined grade of 15.
- Lv 35 Crystals are gotten from breaking +6 Greek Chroma's, +7 ELN's or +8 Blue Serpent Armors.
- Shiny Crystals drop from areas below lvl 100 that aren't premium areas.
- Amrita is a cash shop item that is often given away in events
- Only known location is the "Warped space time room of Lucifer's Castle".
Sources:
Wordwood and 2ch wiki