Sometimes you'll get cosmetics that extens the dodge roll or the invuln time. Those are gold for this challanges
sometime i beat long-legged mushroom with no damage challenge, it only took me 3 hours to finish😀
As for the player, it will be very uncomfortable when touching the long-legged mushroom and the long-legged mushroom use skill to attack it will be very annoying but the long-legged mushroom has 50% health, it will be much more difficult ;-;