Create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is one plus the total number of instant and sorcery cards you own in exile and in your graveyard.
2021-04-16
If you own face-down cards in exile, they won't count toward the value of X, even if you're allowed to look at them and you know they are instant or sorcery cards.
2021-04-16
Serpentine Curve itself is not yet in your graveyard when you determine the value of X.