Arahbo, Roar of the World If youre building around Arahbo, Roar of the World, youre doing cat typal
From there, you have other cute effects such as Paradox Haze to provide you with extra upkeeps, Phyrexian Arena for more card draw, As Foretold to play cards for free, and at the end of the curve, you have decent cards like Xanathar, Guild Kingpin or Extravagant Replication that can push you ahead in games
One last thing needed to fit to produce a set that brought these two sides, fairy tales and Arthurian legend, together
Furthermore, its Loyalty-gaining ability let its controller cast all spells at Instant speed, creating a huge imbalance
We tend to send him in early even into open mana, because the card advantage matters more than the four points of damage