Lucky for yu, i already defined those var's. I made them in tha NTConfig.ntl.
var Im_In_Normal = me.diff == 0;
var Im_In_Nightmare = me.diff == 1;
var Im_In_Hell = me.diff == 2;
Which made it work when yu did that. Just incase yu are wondering why i made these already is because i used tha 'Im_In_Normal' For tha CubeAmu script, so it only did cube in normal when ran. I cant remember if i used nightmare, but put it there just in case.
And wit tha buying potions yu would have to edit yur NTTown.ntl dont know exactly where, but killziky does ^^