That's a chart from the source working on the flawed concept that Darkness=Umbral and Light=Astral.
Urianger explains that what the source understood as 'Astral' is actually high energy states/entropy, and is not responsible for Light, but for Darkness, and vice versa.
This is how Umbral aether, responsible for stasis, low-energy states, can be associated with Black Rose (halting individuals aether flows) and Light magic on the first (fixing aether in place, the stagnant empty)
Thus Umbral, closely aligned with Light, is associated with more static, low energy elemental magics, slow flowing Water, rigid Earth, and Ice being the most static of them all.
Astral therefore being associated with higher energy states, fast moving Wind, and intense Fire and shocking Lightning. Higher energy states lead to higher entropy, the aether flows more quickly, it dissipates and what's left behind is darkness, the Void.
The elements aren't aligned by the black/white triangles, in fact those don't make any sense and conflict with all of the other lore in the game. Rather, they're aligned
top to bottom.
Top = Wind, Lightning and Fire. It's labelled 'Light' on the flawed source chart, but the correct term would be 'Astral'.
Bottom = Water Ice, and Earth. It's labelled 'Darkness' on the flawed source chart, but the correct term would be 'Umbral'.
The error is that Light and Darkness are interpreted the wrong way around, as Light magic is derived from Umbral aether, not Astral, and vice versa.
I expect the black and white triangles are just to do with elemental resistances. That's the only explanation I can think of for their existence.
