Is he the best old junk in /v/?

Two enemies, one is the has the eldritch spear + spell sniper combo able to attack the party from 300+ ft away, the other is his spotter with eyes of the eagle. I want to build an adventure around these two as the main antagonists. How do I build the encounter so the players get feeling of taking cover from sniper fire trying to figure out how to reach them without getting blasted that would be fun and engaing?