Relic
Arcane Energy Crystal
Legendary
Effect
Whenever a 
Mage or 
Mystic casts, they deal damage equal to 100% of their Magic to all enemies and apply Shields equal to 1000% of their Mana Regen to all Heroes.
Where it drops
- Auction House (Legendary Relics)
Other Legendary relics
Questions people ask
What does Arcane Energy Crystal do in Guildrun?
Whenever a Mage or Mystic casts, they deal damage equal to 100% of their Magic to all enemies and apply Shields equal to 1000% of their Mana Regen to all Heroes.
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.