Sentry

Base

Place an untargetable Sentry spirit at target location, granting vision within a radius. After a short delay, the spirit will become active and will chase after an enemy hero if they approach.  Upon reaching the hero the spirit will haunt them, granting vision of that hero for a short duration.

Upgrades

Level 2:

LONG CASTING RANGE: Increases the Sentry placement range  

OR

INCREASED VISION DURATION: Increases the duration of the Sentry spirit  

Level 3:

STEALTH DETECTION: Sentry spirits now reveal Stealthed wards and units in the area.

OR

MULTIPLE SENTRIES: You may now place a second Sentry spirit within a short duration of placing the first.