What is the use of the prop Merken in DotA?

Meken Rejuvenation Aura (Passive): Increases the life regeneration rate of all friendly units within 500 range by 4 points/second. Vitality (active): restores 250 points of life to friendly units within 750 range and increases armor by 2 points. Units that receive the Mekonsm +2 Armor gain are not subject to repeated casting of Imperial Protection during this period.