Temporary control of enemy pieces is a super sweet mechanic that I can't believe hasn't been done yet (outside of mercs). Super creative and I'm glad you found the design space. I think you can push the concept even further though, especially since your action economy with these fellas are a little limited. Maybe something like the infected warrior can bring a spore with them out of the clearing. Helping with your spread and giving a bit more for it to do.
Death burst is also really fun! I think it's balanced the way you've got it, but I almost want it to trigger when an enemy falls in battle... Rather than removing a separate warrior afterwards. Tho I'm sure the way you have it is more balanced honestly.
Really easy to follow and I love the concepts you're going for here!