Last question I promise. Can a portent of far be used to re-roll a 1 when determining how many hits you do? For instance, lets say you cast portent of far on the slann. Now say the slann casts a d6 strength 4 magic missile, and rolls a 1 for hits... is this rerollable? It says you can re-roll to hit and to wound and this would technically be the "to hit" dice. Thanks for your help.
Technically speaking you have already hit, just determining how many so there is no "to hit" dice. So no you can't re-roll a 1 when determining the number of hits.
Completely true, the dice for the number of hits can't be re-rolled, the to wound rolls however can be