Could be a feat, enhancement, epic destiny or a combination of such.
Would involve the ability to have more then one summon at a time combined with better control over and abilities for summons, hires and pets.
Control would be something like setting the aggression level, use magic over weapons, use ranged over close combat, give life for it's master.
Would also involve the ability to drain the masters hp for puppets hp and vise versa (like that priestess does in impossible demands).