Scroll of the Masters
Artifact
Whenever you cast a noncreature spell, put a lore counter on this artifact.
, 
: Target creature you control gets +1/+1 until end of turn for each lore counter on this artifact.
Lake Hurwitz
Fate Reforged (FRF)
• #163Rulings
Count the number of lore counters on Scroll of the Masters as the activated ability resolves to determine how big a bonus the target creature gets. If Scroll of the Masters isn’t on the battlefield at that time, use the number of lore counters on it when it left the battlefield.
(wotc • 2014-11-24)
Once the activated ability has resolved, changing the number of lore counters on Scroll of the Masters won’t affect the bonus that activation granted.
(wotc • 2014-11-24)
Rulings
Count the number of lore counters on Scroll of the Masters as the activated ability resolves to determine how big a bonus the target creature gets. If Scroll of the Masters isn’t on the battlefield at that time, use the number of lore counters on it when it left the battlefield.
(wotc • 2014-11-24)
Once the activated ability has resolved, changing the number of lore counters on Scroll of the Masters won’t affect the bonus that activation granted.
(wotc • 2014-11-24)