As of right now, I believe we get the message "You cannot cast this in town." I believe in era you COULD cast it.. it'd just get you whacked.*Casting offensive spells in town, including the Summon and Field spells and those listed below, is forbidden and subject to punishment.
Any offensive spell cast in town will do no damage, but casting them will flag you as a criminal.
Clumsy
Curse
EQ
Feeblemind
Mana Drain
Mana Vamp
Mass Curse
Paralyze
Wall of Stone
Poison
Weaken
This is the way I've always remembered it, and now it seems like it's a "who's closest" ordeal. EVs should go for the highest Int char in a vicinity and BSes should go for those with tactics and/or parrying.*Blade spirits are geared to track and attack warrior types -- namely, characters with high tactics and parrying skills. Similarly, Energy Vortex track and kill mages and other characters with high intelligence.
Right now, it just seems to damage you.. but it should also make you "fall" (the death animation) and it should temporarily freeze you from moving.*Earthquake is a destructive spell, but it can also help you make a grand escape. A wide-radius spell, it causes all characters within the area (except the caster) to flop around on the ground and injure themselves.