I was able to get through Hard campaign with a 75 card brick/magic deck focused only on building up the Castle. Very important that you have Steal though!
"Problem with level 92 is that that symbol is referred to as many different things... Biohazard and nuclear are examples, but the answer is apparently _______"
The biohazard symbol is completely different and would make for an insane level in this game.
 "Castle Wars 2"){kind=icon}
 "I Love Traffic"){kind=icon}
 "Exploit"){kind=icon}
 "Mushroom Revolution"){kind=icon}
 "Super Stacker 2"){kind=icon}
 "Perfect Balance"){kind=icon}
 "Meat Boy"){kind=icon}
 "Z-Rox"){kind=icon}
 "Fantastic Contraption"){kind=icon}