The Silver Token
This is the nickname for most cards with mana costs requiring spending multiple colors of mana to cast them.
The Gold token.
Almost functionally identical to Treasures, Gold tokens have an aesthetically-pleasing link to gold cards. The former can provide you a mana of any of multiple colors. The latter requires multiple colors to cast.
Silver-framed cards (not to be confused with silver-bordered cards).
Nowadays, these frames denote artifacts (well, Vehicles have a brown frame with some bits of silver flair). It’s common for artifacts to have generic mana costs. Use any land’s mana to cast these. You can even use a Gold token. But what about using…
The Silver token.
These don’t exist in Magic: The Gathering currently. If they did, I think they’d look like this (Gold token for comparison):
In the same way that my brain feels happy knowing that Gold tokens help me cast gold cards, Silver tokens helping me cast “silver cards” also give me joy.
“But We Have Standard(s)”
I know Treasure tokens having a tap symbol in the activation cost means there’s wiggle room in design for punishing Treasures (“artifacts enter the battlefield tapped”) or pulling the punch on Treasure creation (“create N tapped Treasure tokens”).
(Also that the impetus for designing Treasure tokens was that the Standard environment at the time had the mechanic improvise. But that tap symbol requirement is now a handy tool for design.)
But that doesn’t mean new cards that make tokens with “activated abilities that sacrifice yet don’t have the tap symbol” can’t be designed. Where there’s a place for it, it can be done.
Like with bringing back Gold with The First Iroan Games or returning the mechanic investigate. Or with the newer Shard tokens created by Niko Aris:
You can say that Gold and Clue tokens already have the legacy baggage of being designed during a time that was before Treasures existing (2017 is when Ixalan introduced Treasures).
However, when it came to designing the Shard token, which has a similar function to Clues; the designers opted for a token that didn’t have a tap symbol in its activation cost.
(I know there’s a couple arguments with how Shard tokens don’t set a precedent: 1) Shard tokens are not a set-wide mechanic. So their impact isn’t as great to want to be wary about a lack of tap symbol. 2) Enchantments don’t normally do “tap symbol things” like artifacts do. It’s helpful to separate the “feel” of enchantments and artifacts with this logistical difference.)
I think making sure Silver matches Gold is important to the token’s identity.
Even if a premier set that contains Silver tokens as a set mechanic doesn’t have the same Standard problem as Ixalan did, you might still be hesitant to introduce Silver tokens in such a set. After all, premier sets that introduce new design concepts set the tone for what’s the latest and greatest in design principles.
That’s all right — consider that Modern Horizons 2 exists where it goes bananas with having multiple artifact token types in the same set. Something that premier sets don’t normally do. Or the fact that cards from Commander Legends, Conspiracy, and Battlebond are all insulated from every Constructed environment except eternal formats. (And if you absolutely have to, you can pull an Unstable and force the illegality.)
Okay, but with all these different ways to justify introducing Silver, you might ask: why do it, though?
I believe Silver tokens has fun untapped design space and can play around in areas Treasures have been limited on.
For example, blue’s relationship to Treasures is awkward. Red should be the best at Treasures. But blue is best at Pirates, and Pirates are best associated with Treasures. *sigh*
It’s a bit better for blue to have access to creating Silver tokens since that’ll do away with “allowing blue to generate mana of any color” problem of Treasures. I’m not saying to always give blue Silver going forward. Just that, for one set, we can let Silver shine a light on blue a bit more than Treasures have been.
And because Treasures can fix mana so well, you have to be careful of how much Treasure you have in a set. After all, if you have enough Treasures, you might just be enabling a 3-color-decks environment (if that’s what you’re going for)!
We’ve already seen Eldrazi requiring colorless mana specifically to pay for costs. And the solve for that was using Eldrazi tokens that sacrifice. Silver tokens can fulfill the same role, only with the twist that these tokens aren’t creatures.
Gold tokens can’t help you pay for costs with a colorless requirement like Silver tokens could.
Lastly, there are applications of gold (or the generalized Treasure), flavor-wise, that silver just does better. For instance, silver is used to slay Werewolves (or fight other types of monsters and undead, depending on your setting).
Much like how the Adventures in the Forgotten Realms cards had cards that cared whether you spent Treasure on them, you can have cards that are “silvered” when you spend mana from a Silver token on them. And then use these to fight silver-weakness creatures.
And there are other mythologies surrounding the element silver, specifically, that gold or bronze doesn’t fulfill.
Silver Doesn’t Have to Be Second
I believe there’s a home in Magic: The Gathering for Silver tokens. There are places Silver can go that Gold can’t. After all, Karn is silver for a reason.