D20 Reasons Why Werewolves, Devils, Wights, And So On Are Vulnerable To Silver

1. Silver is the metal of the moon, a mistress who brooks no beastly stain on the lullabilic rapture of her night.

2. Undeath, devilry, and were-beasts are all fundamentally expressions of sickness, whether biological or spiritual. The prophylaxis of silver counters them at the root.

3. The undead, demonic, and were-beasts all share an infernal origin - the sulphurous components of their body oxidize rapidly in contact with silver, burning them from within.

4. A silver blade was used by the Great Hero to dismember the Primordial Beast and thereby create the material world. Silver weapons gain mytho-potency by this archetypal remembrance.

5. The demon Beleth was betrayed by its fellows and imprisoned in silver - all silver. Its rage slips through the gaps in its prison enough to especially harm its betrayers and their corrupted creations.

6. Silver resonates with the silver cords that bind spirits to bodies. On ordinary living things it does no more damage than steel, but with beings that are driven by the spirit more than the body it's anathema.

7. The magic which sustains these creatures responds to will structured by belief - the collective superstition that silver must harm them means that it does.

8. The powers of the underworld once made pacts with all the precious metals, but broke theirs with silver in favour of gold - thereby making gold the more precious of the two, and silver still seeks its recompense in blood for this slight.

9. Silver is a relic which remembers an older age of humanity - appropriately, our silver age. This lingering remembrance of glory grants even those in this fallen, iron age the strength to fight the monsters of the night.

10. Silver's close association with coinage imbues it with the energy of civilization - inimical to the devourers of mankind.

11. Silver is the backing of mirrors - mirrors which reflect images, such as images of humanity which in turn are the image of God - those who betray this derived image, through undeath, therianthropy, or demoniac corruption, are destined to be destroyed by it.

12. Some quirk of their biology (or abiology, as the case may be) causes them to suffer rapid and sometimes-fatal argyria on contact with silver.

13. Silver, like dogwood, has been cursed since its involvement in the death of Jesus - for being built into the cross for the latter, and for the thirty pieces paid to Judas for the former. When cursed silver is wielded against evil it creates an effect like multiplying a negative number by another negative number - Satan's house is divided against itself and turned inside-out.

14. Silver is the frozen shadow of mercury - quicksilver - which is the substance of change and mortality. Those things which cling to existence, through immortality or regeneration, are especially torn down by it. Mercury itself would be even more effective, but it's more difficult to weaponize.

15. The cymatic properties of silver cancel out their negative frequencies. All reality's an epiphenomenon of cosmic music, a superstring orchestra.

16. There once was an order of paladins that struck against the heart of hell itself. That order was lost, but the mortal terror of them remains in the soul of evil everywhere - and their heraldry bore an argent tincture.

17. Silver is the highest metal of the sub-lunary sphere, and the ruling archons have empowered it to strike down those who work against their law.

18. Photography really can steal your soul - if your soul's too malleable or detached from your body. Silver, as a foundational material of photography, carries this property by association.

19. The metallic structure of silver coincidentally forms occult symbols which are harmful to the forces of evil.

20. Silver is rooted in the collective unconscious, and reacts violently against the fearsome creatures of the night.