Mass dammage over time?

Undead Fury

Undead Fury

Pre-Searing Cadet

Join Date: Apr 2005

Hi guys nice web ...
For instance i make a necromancer/monk. I gather few summons and keep them alive till next battle. Then i cast "Rotting Flesh" on foes, then "Death Nova" on my minyons, then "Well of Suffering" and "Symbol of Wrath". My question is the following do all that damage over time stacks up or it cancels eachother ?
Please if u know tell me...