At start of combat, the Sentinel with the most items (ties broken by highest Attack Speed) gains a shield that grants stacking Attack Speed. When it is destroyed or expires, it will bounce to the ally with the lowest percent Health and renew. The Attack Speed bonus persists between shield bounces.
(3) 175 Shield, +20% Attack Speed, 4 sec duration
(6) 800 Shield, +80% Attack Speed, 2 sec duration
(9) 2000 Shield, +600% Attack Speed, 1 sec duration