Return to Ravnica Phantom General Rootborn Defenses Sundering Growth Trostani, Selesnya's Voice Populate was the second named mechanic where tokens are a core part of the mechanic
The infusion of red into the work follows the style guide of the set asking for the porcelain white to be aided by red, while also giving us a stronger focal character
Note that Tez can also turn an artifact creature into an artifact creature, so you can make that cool Silver Myr a 5/5 death machine
In the Yorkist campaign, this is dropped (since you're allied with him), but Seto rewards the player with a pendant as thanks for their efforts, telling them to show it to his descendants in their time and pledging his family's loyalty to the powerful Rose Duelist
Ghost Mourner is a little more flexible in this regard, since she only needs to be discarded, but has her own restrictions in only being able to activate when a monster is special summoned