A wizard or elf may attempt to learn a spell he is aware of without spending the requisite time to study, but such an attempt is hazardous. First off, the character must make a check against DC 10 + the spell level as part of an attempt to cast the spell. The initial check consists of 1d16 + caster level + Intelligence modifier.
If this check fails, the character suffers a misfire from the attempted spell. If this check results in a natural "1" the check automatically fails, and the would-be caster suffers corruption as well. In addition, in the event of a natural "1", all subsequent attempts to learn the same spell on the fly reduce the die used for the check, as per the die chain.
However, each failed attempt also gives a +1 bonus to learning the spell if normal research is then used, to a maximum bonus of +4.
If the character succeeds, he has learned the spell! However, the hap-hazard method of learning requires a second Mercurial Magic check with a -20 penalty to the roll. The effects of both Mercurial Magic checks take place whenever the wizard or elf casts this spell.