Let's say you are tossing together a fun Scarif themed Imperial list. TIE Reaper with Director Krennic + crew of choice (maybe that yet unspoiled crew), and a handful of TIE Strikers.
Would you optimize Countdown, to add the shield and lengthen his time on the board by possibly another round, or Pure Sabacc to increase use the shield to require another point of damage to remove his bonus attack die? Which do you think is the best use of the shield boost + shield stripping?