I used to play in a lot of tournaments, and Ive played Magic for a long time
Its definitely powerful in decks with a high density of populate effects and cards that create bigger tokens
It appears that they are explicit abilities, not inherent as in paper Magic, to simplify the rules implementation and type-changing effects in Arena
Eriette of the Charmed Apple Of the three witch sisters, I think Eriette of the Charmed Apple is the most powerful
That gives infinite colorless mana too, actually
The card reads: Whenever one or more nontoken creatures you control die, create a green Fungus Dinosaur creature token with base power and toughness each equal to the total power of those creatures. If your creature dies, it just comes back to life as a mushroom dinosaur