The game won't let you exit the castle, no matter how you try. Technically you can win, but there is no end.

ARTEFACTS AND CURSES

Opal VS Blindness - you forget the map and don't see any new rooms, flares become useless
Pearl VS Forgetfulness - you don't remember where have you been before
Ruby VS Lethargy - monsters get the first turn to attack
Diamond VS Weakness - you lose 1 strength point every 20 turns
Emerald VS Bad luck - your minimal attack power drop to 1 instead of 50% of strength value
Blue Fire VS Bookstuck - book sticks to your hands and you can't attack anyone in this state
Sign VS everything except Bookstuck

SPELLS

Web prevents the monster from attacking and lasts 0-3 turns. Costs 1 point of intelligence.
Fireball is obvious enough. Costs 2 points of intelligence.
IQ instantly kills your opponent if its intelligence is less than yours. Otherwise, you lose. This spell doesn't spend anything.

More details on the official game page of Castle of no Escape ...