I like your colors and shapes, I think what’s lacking there is a good dissolve on your projectiles. They just simply fade out, which doesn’t look good imo. Maybe the knifes could enter the skin of the enemy, the smoke could expand a bit more, etc…
Also the dark cloud from which the projectiles are coming from could appear in a better fashion. Think of two particles moving through soulercoasters (or whatever they’re called) coming from afar, and merging altogether to create this cloud, with some distortion to create impact.
Then the purple outer edge could be blinking/flashing for every projectile shot
Also the cloud fading away at the end works better than the projectiles, but could still be more interesting I think.
How about making it scale up at the end, and dissolve from the center. Much like a smoke ring :
Overall your effect is great, but as you said, it needs some secondary details and polish to work really well !