Poison weapon

Poison weapon is a spell exclusive to the Mephitic spellbook. It requires a Magic level of 80 to cast. To cast this spell, a player must have a poisonable weapon (bolts, arrows, darts, knives, daggers, spears) and at least 1 earth rune, 3 nature runes and 2 death runes. When this spell is cast on a weapon, it turn into either a p, p+ or p++ weapon, p++ being quite rare (1/12). 130 magic experience is granted when this spell is successfully cast.

Uses
This spell can be a cheap alternative to buying poison weapons (which are also usually hard to buy from the Grand Exchange/other players). If this spell is cast 10 times on the same weapon it will have a 100% chance of becoming p++.

The expenses of the runes per spell is 1598 gp (as of May 24th 2010).

Trivia

 * It is possible to receive slightly higher magic xp and a bit of cash per hour then high alchemising, although people tend to prefer the alchemising method due to the convenience of not having to bank.