search for Attack configuration for the sorc and scroll down until you see
//YAM_SorcSkill.push(64); // Frozen Orb
change it to
YAM_SorcSkill.push(64); // Frozen Orb
You can't say; if a monster is immune to fire, use orb, but you can tell the bot to use it as a skill on bosses
you can also change the
//YAM_SorcSkill.push(64); // Frozen Orb
into
PXP_SorcSkill.push(64); // Frozen Orb
for pindle
or
AXP_SorcSkill.push(64); // Frozen Orb
for andy, etc...
Format is [x]XP_SorcSkill where [x] is the first letter of the boss: P=Pindle, C=Countess, M=Meph, A=Andy, E=Eldritch, S=Shenk, B=Baal.