Yeah that sounds fairly solid. Summons is a great skill set when paired with something else like necro or ranger. You are very much broadly correct also on doing one sort of damage. Mixed damage parties are more fun though if harder to be successful with.I ran with Summoner as player char, Enchantress and two physical guys I think. Red Prince and Undead as rogue. Power leveled the Summon early on but I kinda had impression it's better to concentrate on either physical or magic damage.