Glorybringer and The Scarab God might define what five mana buys in the format, but its not hard to play Regisaur Alpha or Charging Monstrosaur for four
The cards are designed with their mechanics first in a spreadsheet, with rarity assigned according to certain stats and text
(When this equipment enters create a colorless 1/1 Hero creature token and attach this to it.) Equipped creature gets +3/+2 and is a Warrior in addition to it's other types
Hazel of the Rootbloom, the Golgari commander heading the Squirreled Away Bloomburrow Commander precon, rewards the aspiring token player with more mana than theyll know what to do with
Six mana is a lot of mana to ask for this effect, but there are tons of ways to generate an absurd board state even if this creature is immediately answered
Heart of Kiran takes a hit since Thorn Lieutenant cant outright crew it, but this impressive card replaces itself if destroyed, cant be targeted or pushed around by aggressive creatures, and it protects from flooding late in the game by providing a 6/7 attacker fore five mana