The Shokz Guide, Starcraft 2 Guide

StarCraft 2 Cloaking Guide

Cloaked units become invisible to the enemy, and cannot be targeted or selected if there are no detectors in the vicinity. These units are ideal for scouting, sneak attacks, harassment, and disruption.

The following units have the ability to cloak:

Protoss

• Observer
• Dark Templar
• Units under a mothership (even allied units)

Terran

• Banshee
• Ghost

Zerg

• Burrowed units will be invisible to the enemy.

It’s important to note that cloaked units aren’t truly invisible. If you suspect an opponent is sneaking around, have a closer look; you may spot a faint shimmer. Watching for said shimmers will enable you to locate cloaked units and, if you have area of effect abilities at your disposal (psi storm, fungal growth, emp), you can strike the general area they might be skulking in. Even if you’ll not be able to select them, you might still be able to cause damage to cloaked units this way. While that works in a pinch, it is better to have detection at the ready to take out cloaked units before they cause significant damage.

Source: StarCraft2.com