The Last Eagle Flies
Member

Outside of Extra Charge and its upgrade Rapid Recharge, there's no other way to directly boost or play around charges. The intention of this item is to provide an explosive opening when playing around with charge based abilities, providing you with a hefty bonus of various stats and a small spirit resist shred for the first charge of your volley. Careful managing of one's charges could also give you a significant power boost, as opposed to blasting someone with all of your charges as fast as possible.
This doesn't build from the previously mentioned items for a reason. It serves as an additional big item for charge builds and a situational lategame item for hybrid or gun builds, who might be looking to round out their slots.
The stats are iterated mainly from Arcane Surge and the flat Spirit bonus provided by Boundless Spirit. Mind you that Boundless Spirit gives you 65 Spirit ALWAYS, this is just for a single casting once in a while, depending on how you manage your charges.
I wasn't entirely sure about the actual stats on the item itself. A bonus charge is given and the cooldown reduction goes nice with that. The weapon damage and movespeed are mainly to round this out as a more flexible item not just for spirit builds.
The tool I used for the item preview has not been updated, so it says T3. But this is absolutely intended to be a standalone T4 item. The name is a reference to the OG Legend of Zelda games, where Link could blast waves of energy from his sword when at full health. This follows similar reasoning.