Backdoor Necrons

A common late game tactic used by necron players to launch all out offensives in Dawn of war soulstorm. A necron Lord teleports into your base and transforms into a deceiver to summon a fake monolith. The monolith can then be used to teleport the entire necron infantry force into your base. Oftentimes the entire army will be flayed ones to spawn camp, or immortals to destroy buildings and vehicles quickly. The tactic is hard to counter, unless you can attack the enemy base as soon as the necrons teleport, or shred the necron army early and fast. The former is better, as a necron Lord may have resurrection orb to raise his entire army back in your base while you recover from the first fight.