Hex Shrunken Head is an epic trinket for DPS casters.
The effective +damage gained from the on-use effect of this Trinket is:
211 * (20 / 120) = 35.16 +damage
Meaning, in total, this trinket grants 88.16 +damage if activated every cooldown.
Patches and hotfixes
Patch 2.3.0 (13-Nov-2007): Added