With one regular hit, additional damage is repeatedly dealt to the target periodically (Damage over Time - DoT). After the Combat Upgrade, DoT's were limited to Bleeding, Fire, and Poison. These could be be administered through combat specials, with specific Commando Heavy Weapons, and through abilities such as the Medic's Neurotoxin. With time, additional DoT effects have been added.
DoT damage can be identified in the Combat chat window by its orange text. The specific debuff can be identified by particle graphics on the avatar, as well as a debuff icon under the target's Health bar.
DoT's can be resisted, absorbed/mitigated and removed, and given time they will dissipate. All DOT's can be cured in at least one way, and Medics has the abilities to cure all of them. While some Food & Drinks offer a nice bonus towards DoT mitigations, the Shard of the Serpent will cap out the absorbtion/resistance for as long as its active.
With Game Update 4 a new type of DoT Mechanic was added that allows the DoT type to be stacked. Some DoTs where converted to work under this new mechanic while others are still using the old mechanic. That means that there are currently two different DoT mechanics, one will allow the type to be stacked, the other one will not. You can tell the difference by viewing the debuff icon. The stackable DoT type will have a number embedded in the debuff image. Only a Commando can increase the stack size to 10.
The list of DoT effects are: