Use this spell if you need to run away from something. The enemy may still be able to hit you with ranged attacks, but otherwise, it can't move to attack you.
Consider using Nature's Grasp if you use this spell to run very often.
Invaluable in PvP against Warriors, Rogues, Hunters, and Shamans.
Use it for crowd control in an instance, if needed.
One of the few crowd control spells not subject to creature type restrictions (humanoid, beast, demon, etc.). It is, however, unreliable. Any creature that is immune to nature spells, as is common among elementals, is immune to Entangling Roots.
Patch 3.0.2 (2008-10-14): Entangling roots is now usable indoors.
Patch 2.0.1 (2006-12-05): All crowd control effects have a chance each second to break earlier, and their duration is capped at 12 seconds in PvP. The chance increases with resistances and the level difference between the target and the caster.
Patch 1.7.0 (2005-09-22): Entangling Roots now shares the same duration in pvp as other long-duration forms of crowd control (ie: polymorph, fear, sap).
Patch 1.4.0 (2005-05-05): Now subject to diminishing returns in PvP. This is considered an immobilizing effect.
Patch 1.2.0 (2004-12-18): Entangling Roots: Rank 4 moved to level 38.