Considering the fire summon appears to inspired by the TES fire daedra, fire immunity may or may not be possible. In Oblivion you could have total fire immunity, but fire resistance was capped at 85% in Skyrim. Either way, you can just stack general magic resistance, spell absorption, or regeneration to safely fondleponder your summon's orbs.
My table always argued it was based on source of resistance so resistences could stack as long as you have multiple sources for that resistance. However redundant instances of resistance were further cut in half. No 100% resistances.