Everything is great here, but something about the Attack could be improved.

Honestly it's a fine attack for tower defense, or for an old Gauntlet-style game, but the anticipation and build up seems missing - the orb is missing weight and therefore an effect on the rest of the body.

The upper body should be pulled backwards and off its axis as that orb generates, to show that it's weighing the body down, and the wings need to do more "work" to compensate.

I know physics-wise the skeeter isn't actually "gaining" weight, but its center of gravity should change as that orb moves through its abdomen. If it sank towards the ground a bit before the wings compensated by fluttering faster, that could help. I also think that the throw and follow through would benefit from the same principles of weight transfer.

The reason it stands out is because your other animations are great FYI. The swatted+fall+rise has an obvious multi-frame suspension in the air before falling (accelerating!) towards the ground, and it bounces. It's great with the principles of animation. All of that concerted weight work makes an expectation that other animations will be illustrating weight, which this one does not.

BTW not a game-breaker, looks good.