User blog comment:Someone456/Someone456's Challenges/@comment-16296785-20130922062006/@comment-16296785-20131015114344

Challenges 8 and 10 are the hardest because Cob Cannons are needed to kill a Giga-Gargantuar, while Umbrella Leaf, Ice-shroom, and Cob Cannon are needed to kill a Bungee Zombie.