Death Shroud is the unique profession mechanic for the necromancer, and can be thought of in a couple of different ways. First, it will temporarily provide you with 4 unique skills, so you could think of death shroud as an extension of your normal hotbar skills while in combat. Death shroud also increases the necro’s survivability while active since incoming damage will deplete your available Life Force instead of your health.
Provided you’ve built up sufficient life force, you can enter death shroud at any time by pressing the [F1] key. Upon doing so, a new bar containing four skills will appear on-screen, though your weapon, healing, utility, and elite skills will be disabled for as long as death shroud is active. To exit death shroud you can either hit the [F1] key again, or it will also end once your available life force has been depleted.
You will build up life force in the following ways:
Whenever a nearby enemy creature or player is defeated
Through active use of certain weapon or utility skills (listed below)
Through the passive state of the Signet of Undeath utility skill
You will typically build up life force very quickly while participating in dynamic events that involve defeating creatures. You can take advantage of this fact at lower levels to both unlock your death shroud skills, and get into the habit of entering and exiting death shroud in combat.
Once you enter death shroud, your available life force will slowly deplete naturally, and incoming damage will reduce your life force instead of your health. The latter helps make the necromancer one of the most resilient professions in GW2, so the faster you can build life force, the greater your survivability will be.
To increase the rate at which you generate life force, there are a number of skills that you will want to consider working into your build. These are listed below along with notes on the amount of life force gained, and the base recharge time for each skill.