Lesser Invocation; 3rd
One of your eyes leaves your head and sprouts spidery legs. You can see through the eye no matter where it goes, so you can use it to scout or spy. The eye can't crawl of its own volition, but you can direct it to move or climb up to 20 feet as a move action. Its Climb modifier is equal to your warlock level +8. You can direct a crawling eye in your space to climb back into your eye socket as a move action.
When you use this invocation, your current and full normal hit point totals are reduced by 2 for as long as the eye is detached. The eye is considered a Fine creature with AC 20 and 2 hit points. Its Hide and Move Silently modifiers are equal to your warlock level. For all other purposes, its statistics are equal to yours.
You can't cast most invocations or spells through the eye, but any spells or invocations that affect your sense of sight—such as devil's sight, all-seeing eyes, or detect magic—function through the eye as though it was still attached. If your crawling eye is destroyed, you are dazzled for 1d4 hours, during which time the eye regrows. (If you normally have only one eye, you are blinded instead.)
At the end of this period, you regain the 2 lost hit points, and the dazzled condition ends.
Only one of your eyes can be used for crawling eye at any time; if your crawling eye is destroyed, you can't use this invocation again until your eye regrows.
Source: Complete Mage