Great little game!
Spoilers for the final level:
I'm not sure how the final level is supposed to go. In my run Big Guy stayed put after clearing the area around the cyst, tanking the shots from the flowers while I peeked in front of them to cleanse the cyst. After a while there were too many bullets to safely peek, not to mention Big Guy's health taking a toll, so I ordered a retreat. After healing Big Guy I noticed the bullets has stopped spawning, letting me sprint to the cyst to deliver the last points of healing. I feel like it was meant to be a challenge where you need to pace yourself and clear the flowers before their number gives them more damage than you can heal, I feel like I cheesed it.