For every two levels of experience past 1st, you gain an additional bolt, which you fire at the same time. You have two at 3rd level, three at 5th level, four at 7th level, and the maximum of five bolts at 9th level or higher. If you shoot multiple bolts, you can have them strike a single creature or several creatures. A single bolt can strike only one creature. You must designate targets before you roll for SR or roll damage.

If your caster level is at least 9th, you grow four additional arms, and the circumstance bonus increases to +8.

Proficiency is granted for only a single, specific item, although multiple castings allow for multiple proficiencies. For example, a sorcerer holding a short sword and rapier, with a buckler strapped to his off hand, could cast the spell three times, once for each weapon and shield.

Note that this spell does not grant proficiency for a class of item, but only for the one specific item held in the hand at the time the spell is cast. Should the caster set that item down or otherwise lose his or her grip on it, proficiency does not fade away; the proficiency is due to knowledge gained, not due to any transmutation of the caster or the item. The caster may therefore recover that specific item and continue to use it with proficiency until the spell’s effect runs out.

Master’s touch does not convey any information about a magic item to the caster. The caster may not even be aware that an item is magical at all.

It's worth noting that the recipient of this spell, though overcome with rage, is by no means rendered an idiot or suicidal. For example, an affected creature will not charge off a cliff in an attempt to reach the target.

While under the effect of a mindless rage spell, the subject can make use of all normal melee combat skills, abilities, and feats -- either offensive or defensive. However, the affected creature cannot use any ability that requires activation or concentration.

An interesting side effect of mindless rage occurs when the spell is cast upon any character capable of the rage ability (such as a barbarian). In these cases, the mindless rage episode counts as one of the character's uses of rage for that day.

Mindless rage is a fairly uncommon spell. It’s believed to have been developed by dwarven fighter/wizards who preferred to face their opponents in melee combat over magical conflicts. Of course, many of the stories tracing this spell's origins to the battle-mages also note that this dwarven method of ensuring melee combat against spellcasters backfired when the group ran afoul of a band of sorcerer/barbarians.

The ray of depletion affects only targets possessing psionic power points. Non-psionic beings hit by a ray register some momentary unpleasant sensory awareness, but not so much as to disrupt an action or concentration.

The spell is used most often to help casters understand the nature and use of an object from another technological level (such as a firearm found in a world where such weapons don't normally exist), or to gain some clues to extremely complex gadgets or puzzles.

If used in the latter manner, however, this spell can prove very, very dangerous. Using understand object to figure out how a trapped device operates can be disastrous, as the spell does not distinguish a harmful nonmagical trap from any other gadget! And, since the spell starts with the easiest or most general effect first (and traps are often much easier to trigger than non-trap functions of an item), understand object may just tell you how to kill yourself.

For example, a character might cast the spell on three interlocking rings found on what appears to be the locking mechanism of a box. The first use of the spell tells the caster that the interlocking rings are, indeed, a locking mechanism and they have to be turned in a certain way to cause a needle to spring out of the box (a trap, though the spell doesn't tell the caster that). On a second use of the spell, the caster learns that turning the interlocking rings also can cause the box to open. Since the interlocking rings have no other function, further uses of the spell reveal nothing. If opening the box causes a fire trap to go off in the opener's face, that is not revealed, since fire trap is a magical effect.