Since stacking different sources of “X Reduced Target resistances” is difficult to accomplish you usually are happy to have 1 per build and never thought much about that type of RR (i know that -X% RR stacks and sources like Viper just take into account the highest number).
However with the incoming changes to Scales as well as Revenant - in case of the effects not stacking that would open quite a bit of options (for example for my ancient Krieg S&B Aether battlemage - Revenant would be amazing boost - but would that stack with the RR from Krieg set as well?).
