At the beginning of combat on your turn, if you've drawn more than one card this turn, put X +1/+1 counters on target creature you control, where X is the number of cards you've drawn this turn minus one.
If you haven't drawn more than one card by the time a beginning of combat step begins on your turn, Proft's Eidetic Memory's last ability won't trigger at all.
2024-02-02 • wotc
Proft's Eidetic Memory's last ability looks at how many cards you've drawn this turn, even if it wasn't on the battlefield when you drew those cards.
2024-02-02 • wotc
The value of X is determined only once, as Proft's Eidetic Memory's last ability resolves.