No, it isn't a spell. It is really a model like any other, 'xept that it is not a unit but an aura. So simply import the model and create a new custom spell on let's say Brilliance aura and redirect the model path to this model.
Negetive aura as instead of adding mana to your units it 'sucks' out mana from enemy units. How to use negative auras u should be able to find in a tutorial section. But it is something under the tab advanced in the editor. Allow negative values... from the top of my head.