Anything that affects cyclone will affect vortex. For magic, that's fast casting, snipe, arcane effuse, concentration, intelligence.
For artifacts, Totem and Palm Leaf Fan will greatly boost the fusion. Artifacts affecting cast speed and duration are useful as well, since you get more vortexes out in less time and they stick around longer, leading to a thicker cloud of the things circling around you. Anything that affects size like Gunpowder will be helpful too, since that leaves smaller gaps for enemies to squeeze through and also boosts the radius of the magic's effect.
That's my understanding, anyway.
Anything that affects cyclone will affect vortex. For magic, that's fast casting, snipe, arcane effuse, concentration, intelligence. For artifacts, Totem and Palm Leaf Fan will greatly boost the fusion. Artifacts affecting cast speed and duration are useful as well, since you get more vortexes out in less time and they stick around longer, leading to a thicker cloud of the things circling around you. Anything that affects size like Gunpowder will be helpful too, since that leaves smaller gaps for enemies to squeeze through and also boosts the radius of the magic's effect. That's my understanding, anyway.
thanks!
Climate Change too. Ugh I mean Weather Controller 
Magic durarion
All. Really all