I think I'll compromise with this " The hitstop maybe you do only for when an enemy dies or when player takes severe damage." After thinking about it, I think it's a great idea to use some sort of screen shake/hit stop when an enemy hits the elemental battery. Great for making it feel more important and like the player took some damage! I think this is the best way to approach this.
Correction, you don't have to select a tower in order to sell it, you can just RMB it.
And yes, I will be adding some particle effects as well as status effects to enemies to know when they are slowed/frozen/etc.
Thanks so much for the feedback. I will add you on discord, you seem like a nice guy/game developer. Look out for MyPing0#6370
Cheers!