Shapers Presence Mechanics on Death aura.

Hello! Im having a bit of difficulty figuring out if
Shapers Presence, from Solstice Vigil. Would be good or bad or both on
a Deaths oath/death aura build.

My main questions are:

Would I take more or less damage from death aura from its effect being slowed.
Would I do more or less damage to mobs from the effect being slowed.