Wet works and Shuriken Akashi

[Barbarjonks]

For X-Force leadership if I use the reroll on an attack and the target is within 3 the defender does not gain cover benefits 

 

for shuriken Akashi if the defender has cover, the dice pool is reduced by 5, 

What is the interaction here, do I determine the cover prior, reduce the pool and if the reroll is used lose out on those dice even though the defender did not have cover? 

[Thoras]

Shuriken Arashi's effect that checks for cover is resolved before Wetworks effect occurs.

So yes, you will "lose out" on the 5 dice.