Black hole damage scaling at 600% effectiveness does not seem to work correctly for generic +spell damage, making it fairly difficult to scale.
Upon testing using a few different sources, adding +3 flat spell damage gives very close to 1/6 the damage value of adding +3 flat spell fire damage, which seems to calculate correctly.
With meteor, 3 flat spell damage adds about 5/6 of what flat fire spell damage adds, which is about what would be expected from the general estimation of the tooltip.
I posted this in the discord skills bug reports as well, but figured I’d post in both because I’m not sure which is more easily viewable for you guys. Thanks for the work! 