So, I have this idea for a sort of deathy-themed hero. My first thought was a gold or plat skill that allows repeated self-resurrection. I know, awful and annoying, but I was looking for things that aren’t in the game yet. I was thinking that s/he could absorb healing while dead and after a certain minimum (50k? 100k?) get back up…more than once, if needed.
I was also thinking of a bronze or silver skill that hurts teammates in exchange for a big boom—maybe self-healing, maybe damage. Or hey, that hurts all other heroes in exchange for a big slug of healing that rolls into temporary health if/when it passes his max health.
His other active skill and other passive skill should be death-themed, too. Maybe a minion summon or—there isn’t one of these yet—a resurrection cancel. Maybe a passive that summons something undead-looking from a downed enemy, which then makes a melee attack and repeats it every 20 or 30 seconds.
The second passive skill could also just be a boost of one of the active skills, like we see on a lot of existing heroes (Ryker gold, etc.).
I’m really liking the idea of a melee minion summon. Maybe summoning it saps HP from allies, and if one of them dies from this then the minion gets a boost for 20-30 seconds. 
The drain/heal could be a bronze called something like Lifethirst. It starts out damaging only allies, then adds the opposing team as a gold upgrade or part of a gold upgrade.
The minion summon could be a silver named Deathcall or Dead Call or something like that. No more than three of these minions, of course. Maybe capped at 1 or 2, depending on how strong they are. Either corpsey-looking or shadowy ghost-wraith things. Ooh, maybe creepy green glowing ghosts or corpses, since I’m picturing Necros as a biochem. Maybe looking soldier-ish, if possible.
And you know, I’m thinking now that maybe it’s not a good idea for both of his active skills to drain team health, so maybe the summon doesn’t. Or maybe it does, but the bronze Lifethirst doesn’t and instead is a strong vampiric attack—probably stronger than any existing vampiric (Callidus, Maven), especially on the healing end.
Hmm, and maybe the minions grow stronger the longer they go without taking damage? Or maybe that can be part of a plat/gold upgrade.
The plat or gold resurrection ability needs a name something like “Death Cannot Die”. Wow. Just the name alone sounds like plat material. After he drops he sponges up all healing, friendly and enemy, for a few seconds—probably not more than 6 or so. After that he’s a valid target for friendly healing (which means he eats all of the “lowest health” stuff and gets in on area effects) and at some point he hoovers up enough healing to resurrect. Maybe as the skill ranks up, the threshold for resurrection goes down (that would be another thing that hasn’t been done on any other hero that I know of). Like maybe “after consuming healing equal to twice his max health minus x, he resurrects at y health”.
Now I just need a name for the gold skill. I want to stick with the life-and-death theme, so an adjective like Living, Unliving, Night, Grave, etc. Maybe the skill buffs both Lifethirst and Deathcall. Or maybe it just buffs the one that damages allies so that now it also damages enemies (and triggers a special if an enemy or ally dies from that), but it also gives Necros some bonus health and/or biochem damage.
For faction I see him as a Mercenary. Or maybe a member of Kurtz’s inner circle, either vanilla KLG or the first of a new “KLG Inner Circle” faction.
So putting it all together:
NECROS
Field Necromancer
Biochem, Mercenary
Bronze LIFETHIRST or LIFEDRINKER: Deals X damage to targeted enemy and heals lots of health (way more than the damage dealt), with excess healing as temporary health for at least 15 seconds.
Silver DEATHCALL or DEAD CALL or GRAVE CALL: Deals a small amount of damage to allies and summons/creates a wraith (or walking corpse) that makes melee attacks, gets a buff for each ally killed to summon it, and grows stronger when it’s ignored.
Gold NIGHTLORD Deathcall now deals a small amount of damage to enemies as well, and triggers the same bonus if this kills them. This hero gets X bonus health every few seconds (possibly linked to wraiths), and bonus health from Lifethirst no longer expires.
Platinum DEATH CANNOT DIE When this hero dies, all healing (friendly and enemy) is redirected to him for six seconds or until he resurrects. After six seconds he is a valid target for healing by allies. After receiving healing equal to his maximum health minus X, he resurrects with Y health.
Basic Attacks: his weapon shouldn’t be either a buzz-gun or a slow-firing sniper rifle. Something in between, like a shotgun or a quick-firing rifle. About 1-2 rounds/second. Or a weird Special weapon with a similar fire rate.
There, one hero brainstorm completed. Thoughts?