Relic
Duelist's Momentum Engine
Legendary
Effect
Heroes gain 40 Attack Speed.
Whenever a 
Duelist auto attacks, they deal 5 bonus damage for each time they have auto attacked this combat.
Where it drops
- Auction House (Legendary Relics)
Other Legendary relics
Questions people ask
What does Duelist's Momentum Engine do in Guildrun?
Heroes gain 40 Attack Speed. Whenever a Duelist auto attacks, they deal 5 bonus damage for each time they have auto attacked this combat.
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.