Patch 3.3.3 (2010-03-23): Now has 3 charges, up from 1.
"Nature's Grasp is a self buff that causes things that hit you to become rooted. That effect now has 3 charges. There is a small internal cooldown in between roots to keep say a rogue who hits you twice very quickly from wasting two charges."

Aparentemente el ICD es de 1,5 - 2 segundos... Cosa que en Trinity Core no está andando.