The spellcaster must make a melee touch attack against the target. The caster need not touch the flesh of the target in order to have the spell function correctly. Once touched, the target is allowed a Fortitude save to completely avoid the spell's effects.
Those who fail the save are transformed into 1d4 Tiny vipers per point of current Constitution. For every ten snakes that are created as a result of the transformation, once 5 foot by 5 foot square of space is occupied. Once the target is completely transformed, the caster has the option of exerting mental domination over the swarm. if the caster chooses to remain in control, the vipers may be commanded en masse as a move-equivalent action. The swarm moves at a speed of 20 feet and makes attacks according to the will of the controller using the statistics provided. This control lasts only for one round per caster level of the caster. if the caster has no desire to control the snakes, the swarm dissolves and the individual vipers scatter seeking refuge.
Successful uses of dispel magic or polymorph within one round per caster level forces the serpents to reform into the target, even if only a few of the serpents remain. After that point, only a wish or miracle will restore the target.