After the newest updates the Persian Sapper has become a very strong tower destroyer, super fast, high damage and relatively tanky. They are very viable in 1 wave tactics together with a Dragonfly and Huge Mighty Rage. Only weakness is that they move too fast and Gentle Healer have trouble keeping up with them.
Persian Sapper is immune to traps while underground, it can trigger a trap that is really close to its target but normally it won't trigger any Buried Spikes or Fire Traps. These mercenaries can also dive underneath walls if the pathing is not too far.