Rule 832.1.d.1
The information referenced in this way is checked when the card/s in question are shown off during finalization. Any later changes to the shown off objects will not be considered. Example: Primordial Roar is played showing off a friendly unit with 4 [M] and an enemy unit with 3 [M]. In reaction to Primordial Roar, an opponent plays Frigid Touch, giving the friendly unit -2 [M] this turn. Because the information was checked when the friendly unit was shown off, the spell still deals 4 damage to the enemy unit, killing it.