I was testing a shrine deck with the card exponential growth, taking advantage of the ability of the card Sanctum of Fruitful Harvest along with Sanctum of All and Mirror Box, in order to obtain a total of 120 green mana. Then, I cast the spell exponential growth with a value of X=64 (128 mana cost), targeting a creature with a power of 124/128. The result of this creature's power after the spell should have been 2,287,396,265,139,984,400,384. However, the creature's power ended up being 0. I imagine that the game's programming doesn't account for such a high multiplication, but I wanted to make note of it. Thank you for your attention.