So it took me fifty tries and a walkthrough to beat the second bonus level. I look at the one piece of advice on level three that's in the comments, and I beat it on the first try.
I think they should add another Hard or Impossible badge with the sole requirement of not being hit on the last level. I think it'd be possible, with luck and careful planning.
I see that there's a red deck in the top comments, but here's another deck that swept all 8 challenges on the first try, a 23-card Black deck. 1x Contamination, 2x Memory Serpent, 2x Azure Minion, 2x Blackguard Spider, 3x Disintegrate, 3x Blackguard Thug, 5x Blackguard Leader, 5x Drain Life. For the Challenge against the opponent with 100 Health, try to avoid doing damage until you can play Contaminate, and then finish her off.
Flies: "Huh, interesting." Ladybugs: "Cool, more health and webbing." Bees: "Annoying little buggers, but I can handles them." Stag Beetles: "You are the architect of your own demise! Your gold thread can contain you!" Fireflies: "You know, swarms of moths are kind of annoying... but it's a load of webbing when I eat you, so okay." Butterflies: "How can something that delicate be that strong?" Dragonflies: "My new best friend. Omnomnomzoom." Queen Bees: "GOD**** IT YOU ****ING SON OF A *****!! THREE QUEENS AT ONCE?!?!" Hummingbirds: "Goodbye, little birds! Enjoy the big hole the queen bees made for you!" Bats: "I AM THE SHADOW ON THE MOON AT NIGHT! FILLING YOUR DREAMS TO THE BRIM WITH FRIGHT!"
... No. No, no, no, no. GREENLAND AVOIDED MY DISEASE?? Madagascar got infected THIRD, and GREENLAND survived?? Everyone else died within a hundred days, and Greenland's sitting there, all green and happy, the smug bastard.
Super Carrier backed up by Cruisers, Tankships, and Light Carriers. Final boss? What final boss? I'm sorry, I couldn't hear you over the sound of my swarm obliterating everything.
I run for two minutes before the first foe touches me, and manage to run for over five hundred meters before I am finally struck down. I await the cold embrace of death, only to feel the warmth of sunshine on my back. I look and see that the nightmare is ended. I can sleep. I am at peace. (5/5)
I run through the dark woods, never able to outpace my nightmare. I begin to notice details, even through my panic, and I wonder: Are those skulls mine, topped with the red ribbons? Are they the forest's taunting way of reminding me of my failures?
 "Arkandian Explorer"){kind=icon}
 "colorfill"){kind=icon}
 "Badge Master"){kind=icon}
 "Reactance"){kind=icon}
 "Fairway Solitaire"){kind=icon}
 "Epic Battle Fantasy 2"){kind=icon}
 "Lab of the Dead"){kind=icon}
 "Mytheria"){kind=icon}
 "Pirates Vs Ninjas"){kind=icon}
 "Accelerator"){kind=icon}
 "Arachnophilia"){kind=icon}
 "William and Sly"){kind=icon}
 "Pandemic 2"){kind=icon}
 "Epic Battle Fantasy 4"){kind=icon}
 "Obliterate Everything 2"){kind=icon}
 "Fear Less!"){kind=icon}