Can damage or destroy walls from a distance. Balance: Low HP, higher cost than wall breakers, higher storage requirement, lower damage (so an increased cost in time vs benefit during battles) or any combination there of.
This could allow troops to enter villages with minimal losses at the start, but the risk lies in the loss. If your sapper dies before it can begin, the loss of troops (those not made so the sapper(s) could be) could cause the entire raid to fail.

