Shields are only replenished from activating abilities. Constant Energy drain from channeling abilities or triggered drain such as Artemis Bow shots do not replenish Shields.
Excess Shields are granted as Overshields, but more will not be granted before Overshields are exhausted.
As such, if Shields are full, users should cast their highest cost ability to get maximum Overshields.
Because the amount of shields restored is based off energy usage, this means that Ability Efficiency can reduce the potency of this aura's effects.
Conversely, equipping Blind Rage to decrease Efficiency increases the effectiveness of the aura.
The highest amount of Shields possible to acquire from one ability cast is 232. This is achieved with a fully ranked Blind Rage and casting an ability that costs 100 Energy. Trinity can acquire 240 shields by also wearing the Arcane Meridian Helmet, although Vampire Leech is a better way to regenerate shields.
This is the first aura using the polarity.
Currently no Warframe possesses a matching polarity by default, aside from Excalibur and Nekros who have no innate Aura polarities.