Poison Mushroom Cookie is a tricky boss due to its persistent poison damage. This debuff can quickly whittle down your team's health. A strong healer is paramount here. If you have Herb Cookie, his skill cleanses debuffs, making this fight significantly easier. Otherwise, rely on burst healing to counteract the poison.
Recommended Team: A sturdy tank, 2-3 strong damage dealers (preferably ranged to avoid some poison puddles), and a dedicated healer. Ensure your Cookies are at least Level 20-25. Treasures like the 'Squishy Jelly Watch' and 'Pilgrim's Scroll' are highly recommended for increased damage and skill frequency. Focus fire on Poison Mushroom Cookie to eliminate the source of the debuff as quickly as possible.