SIRs are identified by the "SIR" stamp on the card, the full-bleed artwork extending to the card edges, and card numbers above the official set total (for example, card 199/165 in SV151 indicates the SIR variant beyond the base 165-card numbered set)
But then Tam, Mindful First-Year shows it is alive and well in Standard
Thats not actually the only strategy at work here, though
Sure, the deck isnt super-fast unless you have a starting hand with Sol Ring and Arcane Signet, but with few interruptions, you can get the deck going long before your opponents catch on
When challenging isnt a good option, you can also play Let it Go to send strong characters or readied ones quickly to the Inkwell, facedown where they cant cause any more harm