Slime Fortress - Using Matt will be the fastest way - After he uses the sub weapon,(or maybe I say,Cataclysm) it uses only 1/2 or 1/3 bit of the Cataclysm bar,so he can use it 2-3 times.Also he starts with an extra bomb so spend it to defeat the boss.Yep,it's simple with Matt.(Don't rate down,if you feel this is bad just ignore it.)