Running a homebrew campaign where werewolves are the main threat. I never hid that fact from my players so naturally they got their weapons silvered at the first chance they got.  I expected them to do this, so I have some contingencies in mind. 

First is a spell for the enemy clerics called Disarming Rebuke. The idea is it's a reaction spell that the caster takes when they or an ally is hit by an attack. Spell creates a glowing sigil that protects the target by forcing the attacker to make a Charisma saving throw. On a success the hit becomes a regular attack roll instead of a crit, but on a fail the attacker's weapon is wrenched out of their hands a distance of 10 feet. I want to include a feature of the spell that breaks weapons, but I don't know how to implement that in a way that's not unfair. 

I'll also have spells like heat metal and an enemy Battle Master for cases when they're fighting werewolves as well. What other tricks do you use when your players bring out the silver weapons? 

I assume that PCs have silver weapons and rely on the standard tactics of massive violence.

They silver plated their weapons the first chance the got. Like i said, i expected this, but now i cant make it too easy for them. 

 They're also one of the more intelligent groups that I've played with, so they know what they're doing, both in roleplay and in combat. 

I would probably go down the route of having the werewolves start wearing heavy armour, and responding to the presence of silvered weapons. Werewolves usually rely on their immunity, but if they keep falling to the party (and I will emphasise, let them fall near the start - make the PC's think they've won) then they should see some repurcussions i nthe wolves:

• The wolves start using ranged weapons, including nets and chains to try and disarm them
• The wolves start wearing heavy armour, making them harder to hit
• The wolves start developing a potion which removes their vulnerability but sends them into a blind rage, eventually killing them
• The wolves develop magical armour which transforms with them. Think werewolves in power armour.
• Heat Metal - for flavour, have them watch as the silver drips off their glowing-hot blade!

I emphasise again, make the change slow - they spent money silvering their weapons, so should reap the rewards, for a while!

Silver weapons and werewolves are an odd little thing in DnD. There aren't many uses for silver weapons, but when you need them, you really need them. Most games never see a werewolf at all. If they do, it's usually a rare enough occasion that it's okay if some characters aren't prepared.  They get creative, use spells and fire and maybe a magic weapon.  The werewolf is weak enough that it won't break anything by that point.  It's just a fun one-off fight. 

But if you want a game full of lycanthropes, you have this kind of problem. Everyone gets silver, and the immunity has no meaning.  You can take their tools away, but if do it too much they feel cheated. I can think of a few options that might work. 

1 - Let it happen. Don't worry about it.  The players were smart and that's good.  Show the werewolf immunity off in other ways.  If NPC guards are breaking swords on their hide, the players will feel like heroes when they run in to save them.

2 - Lean into it.  Let the players cut through normal werewolves with silver the way Blade does vampires. Just let them go wild.  Have tons of minions that they can feel awesome beating.  Then have some tougher ones that play by different rules. This one is more work to implement, but could be fun. The only problem is it begs the question of why everyone in the world doesn't have silver weapons. 

3 - Make the werewolves smart. They know their weakness.  They will do everything to avoid it.  Surprise ambushes, spells like you mention, disarming battle maneuvers. A werewolf that had to face a silver weapon would take their first attack to rip it from the character's hands. Smart monsters are great, but if they're too smart you could be accidentally setting up a TPK.

4 - Change the rules.  It won't take much.  This is a werewolf focused campaign. I think it's okay to homebrew some, and your players will probably understand. Say that the werewolves are immune to normal weapons, and are RESISTANT to silver ones. It can hurt them, but not as much as magic.  Or just double their HP.  This is probably the easiest solution. 

Hope these give you some ideas. 

Quote from Dr_Von_Genius >>

They silver plated their weapons the first chance the got. Like i said, i expected this, but now i cant make it too easy for them.

Werewolves without their damage immunity are still decently dangerous, they're roughly the equivalent of CR 2 at that point. If you need more dangerous, give them special abilities, class levels, or whatever.

Lots of great ideas so far, I’ll add a few silver coins to the pile!  

It sounds like werewolves are going to be very common, so change up the vulnerability to other metals like Gold or Platinum, maybe even Cold Iron.  You can drop a subtle hint like their fur being a different colour or whatever.  This could also set up some interesting quest hooks if those metals are rare or hard to find.  

Aside from that, class levels, tactics and maxing out HP are all great solutions.  Heat Metal is probably your ace in the hole, and it’s on the Druid spell list of that class plays into your theme.

I be hesitant to involve tricks into the mix, because if the characters are prepared, they should be rewarded for this, not have the rug pulled from under them. In a werewolf-heavy world, any adventurer with half a brain would also get silvered weapons asap.

But then, you'd figure if the characters would adapt to the large number of werewolves, then the werewolves would also start to adapt to the large number of silvered weapons. For starters, they'd likely retreat the first time one of them got hurt in a fight. After that, it would be an arms race, basically. Maybe they would develop the homebrew spell the OP suggests. Maybe they figure out how to cast blade ward as a bonus action. Maybe they adopt, train and breed rust monsters as pets -- there's iron under the silver on that weapon, after all.

I'd also agree with Thoruk's suggestions with ranged weapons, and disarming becoming common. For extra fun they could work in teams, one could disarm someone, and another could cast catapult to safely toss the weapon (most weapons weigh less than 5 pounds) far away.

You could also have them start to evolve. Maybe, from all their rust monster training, their blood gains the ability to degrade the silver, like a rust monster does to iron. Maybe they develop an immunity to silvered weapons, and now it will take a platinum weapon to hurt them.

Quote from Dr_Von_Genius >>

First is a spell for the enemy clerics called Disarming Rebuke. The idea is it's a reaction spell that the caster takes when they or an ally is hit by an attack. Spell creates a glowing sigil that protects the target by forcing the attacker to make a Charisma saving throw. On a success the hit becomes a regular attack roll instead of a crit, but on a fail the attacker's weapon is wrenched out of their hands a distance of 10 feet. I want to include a feature of the spell that breaks weapons, but I don't know how to implement that in a way that's not unfair. 

 I would not use a homebrew to counter completely legit tactics by the party. They will feel cheated and unhappy. The other ideas about ranged attacks and such would be fine.

Rust monsters are good idea.

Werewolf Barbarians.

Let the party have fun with their silver weapons for a while before you slap with changes to the dynamic.

Maybe the use of sheer numbers or henchmen or NPCs (especially powerful...politically, magically or physically...like a cult) sympathetic to the Werewolves' cause.

Sure silvered weapons are useful but they don't tell you who is or is not a werewolf.

The White Wolf game Werewolf: the Apocalypse has the idea of kinfolk, people  who are blood related to werewolves but who aren't actually werewolves themselves. These people are obviously not as powerful as werewolves but they also lack werewolves weaknesses. Like vulnerability to silver. Ass Garr_Feyld mentioned, silvered weapons don't tell you who actually is a werewolf. A few kinfolk messing around could easily disrupt the players' plans.

Just because werewolves are the bad guys does not mean it always has to be  a straight fight with werewolves. 

Tactically you can make it difficult to identify wolves from werewolves by mixing the two together.  

Werewolves can also make use of any tactic a human would including having human mercenaries, hiring thieves to switch out the weapons or anything else. I always liked the idea of the werewolf illusionist/ enchanter who uses magic to frame others as the werewolf and bend others into their service. It could be interesting to frame some druids as an example.  I like the spell dream for this as you could appear in peoples dreams as a monstrous wolf and prevent them gaining the benefits of a rest so they think they have been on a rampage.

Recruiting other creatures could also be interesting. Getting an orc clan on side by giving the orc wolf powers and bending them to their will could be interesting.  An alchemist who  makes potions that give strength by imparting a small portion of the werewolf curse possibly even creating weird hybrid creatures is another example.

A transmutation wizard could be a handy thing to keep up your sleeve. As others have said, let them have their silvery fun for a while. But after the revelry, remind them that the DM makes the rules. A quicker/not concentration form of Minor Transmutation would be cool, since it already works with silver. If you describe it well, imagine the terror you could invoke by turning steel to stone. Don't just leave all the martials with nothing, though. Give chances to buy silver knuckledusters as a fall back, or silver oil of sharpness.

Have the lycanthropes have trained rust monsters.

Doubling (or more) monster HP can make the combat last a bit longer and thus make it more challenging, without undermining player agency by circumventing their efforts to be prepared for your campaign. 

Quote from Caerwyn_Glyndwr >>

Doubling (or more) monster HP can make the combat last a bit longer and thus make it more challenging, without undermining player agency by circumventing their efforts to be prepared for your campaign. 

 Werewolves already have pretty low damage and accuracy relative to their toughness; I'd just solve the problem by using more werewolves. Or use a loup garou.

Evidently it doesn't matter anymore, because silver and were anything is no longer a thing in the 2024 system. Kind of a huge kick out of the blue with no explanation.

Silvered Weapons now do extra damage on critical hits against shape-shifted creatures. So they still do something, just different.

I don't see it as a good change.