Is there a list of all creatures in Arena?
If you go to scryfall, and look at all the 9 mana value creatures available in historic you get a list of 5 cards (as of 2021-09-05).
Missing from that list are the cycle of five bringer creatures.
However, if you experiment with Pool of Vigorous Growth you'll see that it will generate tokens from the bringer cycle.
This leads me to conclude that the pool of creatures that Pool of Vigorous Growth pulls from is all creatures in Arena. Which is different from all creatures in historic. (Wizards often has put the bringer cycle into special events on Arena.) Is there a list of all creatures in Arena?
One scenario where this matters: I have a pool on the battlefield, and my opponent is in beatdown mode with a flyer with the ground fully stalemated. I need to get a flyer and have 1 basic land in my hand. How much mana should I pump into the pool to maximize my probability of getting a flyer?