Great game!
I really like the music and it looks amazing, really polished,
I really like the twist you put on it. It makes the wave itself be much more interesting.
I don't really have anything to say, other than maybe you could explain a bit more (specifically explain that you need to pick up the skulls, it's a small thing but I was confused for a bit, I thought the skulls where just there to stay).
You could also make each slime leave a small mark on the ground when he explodes to show the player what happened in the battlefield.
And one last thing, the player is drawn under the turrets and some times it isn't right.
Please make a post jam version!