I don't want to autoban tnt/lava/fire as they are a good part of gameplay. You can quickly build a tunnel with strategically placed TNT, build a monster trap with lava or secure your evil castle, make a fireplace with fire.

But people have to be responsible using them, and not go "HURP DERP! TROLOLOLOLOLOLO I just blew up the building with TNT LOLOLOLOL!!!!111"

"Sometimes JCL reminds me of Notch, but more competent" ~ Kiyaku