[Autumn]

It doesn't require you to hit a wall, just that you fail to complete the knockback.

Since it apparently is not a bug, I'll go ahead and make it here, being able to spam dense thunder on a target immune to knock back can be highly abusable, as they will take sound magic damage equal to half the original amount, which adds up fast when spammed.

It doesn't seem like it consumes a lot of Ki either in this way.

Perhaps this needs to change to not trigger when a target is knockback immuine, assuming thats a flag of some sort.

[Fern]

Making the sound damage not proc when the target is immune to knockback sounds simple enough. +1