The first set in each generation is always the best place to see this and our switch from Sword and Shield into Scarlet and Violet has made this particularly evident
Illustrated by Aaron Miller, Gandalf the Grey is a 5-mana legendary Avatar Wizard, and in typical red-blue fashion, it triggers whenever you cast an instant or sorcery spell
Lampent takes 20 additional damage from Water-type attacks
Finally, I was much too high on Foul Emissary, who has not seen more play because of how badly he matches up against Liliana, the Last Hope
One way WotC can achieve that is by reprinting cards that are in unusually short supply
I dont think this would be worth it in most decks, but it could be a cool inclusion in something like Nymris, Oona's Trickster, which frequently passes with mana open