Relic
Defensive Energy Crystal
Legendary
Effect
At start of combat, 
Tanks and 
Vanguards gain Shields equal to 100% of their Max HP.
After Stall (20 and Stall 40), Tanks and Vanguards gain Shields equal to 1000% of their Defense.
Where it drops
- Auction House (Legendary Relics)
Other Legendary relics
Questions people ask
What does Defensive Energy Crystal do in Guildrun?
At start of combat, Tanks and Vanguards gain Shields equal to 100% of their Max HP. After Stall (20 and Stall 40), Tanks and Vanguards gain Shields equal to 1000% of their Defense.
What is the difference between a relic and an item?
Items are equipped by a single hero and take up one of that hero's slots. Relics apply to the entire guild and do not use slots. That makes relics the stronger of the two when a build starts coming together.
How do I increase my team size?
Harmony Crystal raises it by one, up to five. So does each of the fifteen Mandate relics, but those require finishing an objective first, like dealing 15000 auto attack damage or applying 30000 shields. Pick the Mandate that matches what your team already does.