"Is it the water? The stars? Whatever it is, something incredible is happening here."
—Eris, zoologist, journal entry

Branching Evolution

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.

As Aclazotz's undead forces approached the temple of Ojer Kaslem, they met a roaring wall of vibrant, flourishing life.

Modern Horizons 3

The Master discovered a new evolutionary path after tossing a human, a dog, and a cat into a vat of Forced Evolutionary Virus. He called his creations "centaurs" and unleashed them unto the wastes.

Fallout

If a creature you control would enter the battlefield with a number of +1/+1 counters on it, it enters with twice that many instead.

If two or more effects attempt to modify how many counters would be put onto a creature you control, you choose the order to apply those effects, no matter who controls the sources of those effects.

If you control two Branching Evolutions, the number of +1/+1 counters put on a creature is four times the original number. Three Branching Evolutions multiplies the original number by eight, and so on.