I feel like making a few of these more predictable in their arrival, but also easier to set up would tip them towards being healthier for the playstyles of both users and targets.
- On the topic of Explosion's balancing, Pyroclasm definitely used to offer a larger time window to be evaded when it was a GCD Charge spell, but it also allowed the caster to pop one or two gap closers to get there on time, while structuring a more effective combo with good reliability. It offered a higher risk, but also a higher reward, while not being a guaranteed combo starter.
If Pyroclasm was set to healthier standards, I wouldn't be against seeing Inferno be converted into a Cast Buff that spawns a lingering AoE to follow you around, much like Supernova's passive effect (but actually 3x3 or larger, rather than 1x3). I find this to be more faithful to the spell's name than its current iteration, maybe?
- Black Hole, too, could still retain its delayed activation to justify its high proc damage, but function similarly to Tornado or Spores rather than build itself up stationarily. In an experimental scenario, a charge effect overlaps the caster and after three seconds, the Black Hole is released ahead of them by a range of about 3 or 4 tiles (perhaps more). They can still see it coming, absolutely, but you would at least have a chance to pursue and unleash it at a more favorable spot while capitalizing on zoning them in. Or out?