When does rotting become more viable?

[Brutal_X]

Hello fellow priests and more specifically shamans, I have a question as to when it becomes more viable to root rot as opposed to smashing things.

Currently I am a level 37 ogre shaman nearing level 38. At level 39 I get a few spells including a great new dot, and canni 2. I'm following the evil shaman guide (thankyou Blkcamel for that) and so I am currently killing NK guards. I can slow and smash these with the help of a poison dot pretty easily although sometimes they hit a little hard if RNG isn't on my side. My question is -- when I move to a different hunting spot and mobs inevitably hit harder, will it be more effective for me to switch to shield and spear (for more mana) and root rot?

Thanks in advance for any input guys, it's much appreciated.