In both his hero units, Duran has the ghost's Lockdown and Cloak abilities, but cannot target nuclear strikes. As an infested unit he also has the Consume ability. This makes Duran indispensable for defense in "Drawing of the Web," able to Lockdown powerful protoss units and then Consume zerg to replenish his energy.
Curiously, Infested Duran is the only unit to be upgraded with weapon and armor upgrades from separate factions: zerg carapace upgrades will improve Duran's armor, but it is terran Infantry Weapons upgrades that improve the power of his weaponry.
Duran also has a unique death sound that is in the game data, but not implemented.