Tulips need a nerf, and when this happens firefly cost should be reduced. No tank should be one shotted by another, that is just bad gameplay. This is made worse by the tulips piercing, which is also stupid. When you are using heavy tanks vs. Fireflies you are basically constantly fighting with 50% health since you know he can, and will, launch the tulips as you get low on health. Since heavies cannot maneuver away you have to assume as you reach half health the tactical nuke is inbound. This is both boring and counter to how heavies are supposed to be flanked not approached head on.
I drew a picture for you.