Berta, Wise Extrapolator (SOS-175) - Secrets of Strixhaven

Increment (Whenever you cast a spell, if the amount of mana you spent is greater than this creature's power or toughness, put a +1/+1 counter on this creature.)

Whenever one or more +1/+1 counters are put on Berta, add one mana of any color.

X, T: Create a 0/0 green and blue Fractal creature token and put X +1/+1 counters on it.