Overlord of the Balemurk would be pretty medium without an impending cost of 1B, and its this that takes it from medium to more playable
In fact, you can get all five colors from it
Mannichi from Betrayers of Kamigawa (2005) wasnt quite the last monored card to do this, but red mostly lost the ability, even though it seems to have become a common theme for blue-red creatures
Shall we go ahead and get into things
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Legal Oathbreaker Legal Penny Not Legal Toolbox Notes and Rules Information for Arcane Signet: If you have two commanders, the ability adds one mana of any color in their combined color identities
Witherbloom in the original Strixhaven failed to really come together, but it was split between a lot of different themes, so maybe a central focus on lifegain can pull it all together this time