Actually two different version of Silver Negation. Also, I find myself in the strange position of writing spells for a game I don't own - Labyrinth Lord.
The werewolf Nicolen of Vorla wailed as an arrow pierced her side. She began to snarl a rasping, growling, chant. Seeing her intent the monster hunters descended up her in a swarm, but they were too late. The arrow shot from her flesh as the wound sealed before their eyes, and the swords bounced harmlessly off.
Silver Negation (Type 1) (Mage)
Duration: 1 hour
Area of Effect: 10' from caster, moves with the caster. Weapons entering the area from outside are affected until they leave, those within when it's cast are permanently affected.
Silver Negation causes all silver weapons that enter the area to no longer affect Werewolves, undead, etc.
Full credit for the Wall of Silence goes to Bat of Ancient Vaults and Eldritch Secrets. It was just too good an example to pass up. It can be found here.
Lynette stepped into the center of the web of glowing, silvery, runes. It was a good thing that she'd heard there was a Wall of Silence moving this way a week before it would arrive. She sat down and settled in for a long wait.
Silver Negation (Type 2) (Mage)
Area of Effect: 10'-50' area, does not move with the caster.
The caster carves a circular webwork of runes into the floor, using 100 GP worth of silver for every 10' affected. All spells within this area other than the caster's are negated.