Suggestion: reworking blood magic
Alright now for the explanation. (NOTE: the suggested numbers for vampiric are just that, a suggestion and will need to be tested and balanced.)
To start off I suggest changing the functionality of life siphoning. Instead of its current format where it deals damage and heals independently I recommend making it a 1:1 ratio (eg you deal x damage, you gain x health). Additionally it will no longer scale based on your power\healing power, but instead will scale based on your max health, with the max damage you can do with 1 packet of life siphoning being capped at your own current max hp. Furthermore each unique source of life siphoning (eg: on hit, on crit, minion atk, well damage) will have an internal cool down of 1 second per target, meaning you cannot do rapid amounts of damage to hasten your recovery or your enemies demise. Life siphon’s damage will be determined based on a percent of foes current health (again capped by what your current max health is) or, if traited, based on what their max health is (still capped by your own hp). In pvp the fact that life siphoning will be based on your foes current health (unless traited) means that it will be more effective against higher health targets (warriors\necros\builds that increase vitality) and less effective against low health targets (thieves\eles\glass cannon builds). In pve where enemies will have enormous health bars its important to cap the max amount of damage you can life siphon based on your own hp. This is both to limit the damage you can do to enemies as well as the healing recovered by life siphoning.
beyond the grave: The reason I add this trait is to fix one of the most conflicting mechanics with the necromancer. Currently the necromancer’s death shroud ability, a core mechanic of necromancer, prevents another core mechanic of the game: being able to heal. Since it would be overpowered to allow any source of healing affect you through death shroud this is limited to only what your other allies heal you for as well as the ability to life siphon. Additionally vampiric has been moved up and merged with the other vampiric trait.
blood ritual: with life siphoning gaining a new way of scaling (by increasing your own health) blood thirst is no longer necessary. adding this trait in (combined with changes to unholy martyr) allows necromancers to play a healing\support role which gives necros access to a powerful condition removal and aoe heal (transfusion).
mark of evasion: a 10 second ICD is a bit steep, especially since necros have no source of vigor to dodge frequently anyways. I recommend either lowering this down to 2 seconds, or removing the ICD completely.
vampiric: I covered most of this traits change with the base changes to life siphoning. the reason for merging all the life siphoning traits into 1 is the same reason for merging all the other traits for all the other classes in the game.
vampiric rituals: by adding protection to the end of the well’s duration it incentivises allies to try to hop into the well’s aoe if they missed the protection gained on the initial casting. the life siphoning effect is changed to match vampirics effect.
unholy martyr: This change, in combination with transfusion and blood ritual, is designed to give support necros tools similar to other classes. allowing them to condi-clear easily and give a burst heal at the expense of suffering the conditions they remove themselves.
ravenous appetite: with the addition of blood ritual to boost the effectiveness of transfusion, deathly invigoration is no longer a necessary healing tool to support your allies with. Additionally this trait is meant to “replace” bloodthirst as it makes your life siphoning consistent even when a foes health starts to get low.
Self healing needs to be base, the idea that it requires a trait is absolutely against what this trait rework is about.
Also % HP based siphoning is probably a worse idea than what we have now. Siphoning and related things are best balanced by relating them to damage (the only way to get high life steal is via high damage, so you can’t steal tons of health while being tanky), or relying on investing in tanky stats. An ICD isn’t the worst idea for Vampiric simply to keep it relevant to every build, but otherwise the numbers just need to go up flat, not rely on HP investment (which has all kinds of issues in GW2).