The mischievous Goblin Sappers are known throughout the Horde for their incredible aptitude for destruction. These diabolical Goblins are invariably armed with extremely volatile explosives; which enable them to level enemy structures and weapon emplacements. Although the Sappers are highly unpredictable and insubordinate, they have become necessary to the plans of conquest maintained by the Horde.
Goblin Sappers are fast units with a suicide attack that deals 400 Piercing Damage to all adjacent ground units and buildings when they detonate (enough to destroy a Farm). This is their default action when you right-click on an enemy building or unit.
They will not deal damage if they are killed before they reach their target, even though their death animation shows them exploding.
They can also be ordered to attack normally, but are weak and fragile, just barely stronger than a Peon. If attacked by an enemy unit, their default reaction is to flee.
Casting Invisibility or Unholy Armor on them will kill them instantly.
The computer player is not programmed to use Sappers; if put under computer control in a custom map, they will just stand around doing nothing.