Disclaimer: I know that new classes are unlikely, and if there are ever delved into by ZOS it won't be for a very very very long time. But I wanted to get the idea out of my head, because when things this large get into my head, I won't stop thinking about them until they're written out and scrabbled down. Tis why theorycrafting is so intriguing to this here Panda.
Anyways, I did this when I was bored and had three hours of spare time, all three skill trees with complete skills, morphs, and passives, for what I hope to someday be a build centered around DoTs. Kind of like the Sith Sorcerer in SWTOR, but since it's TES, and a Necromancer class would need three skill trees. Well... yeah... The rest of this just kind of happened. I took inspiriation from a lot of different games, but DoTs. DoTs. Everywhere. Onto the juicy bits.
Necromancer ClassDefiler Skill Tree
Ultimate
Circle of Death (Base Skill) - Summon a circle of affliction to deal massive damage to enemies in the area and snare them by 40%. AoE DoT/Snare, 8m radius. (Drops on top of you like Standard/Veil)
Circle of Desiccation (Morph One) - Stops recovery rate of enemies in the area.
Circle of Mutilation (Morph Two) - Reduces enemy healing received by 50% while in circle and by 25% for 6 seconds after leaving the circle.
Maim (Base Skill) - Conjure a dark cloud around the enemy choking them for 8 seconds. DoT, 24m range.
Lacerate (Morph One) - Snares enemy by 20% and drains stamina for 8 seconds after effect ends.
Mutilate (Morph Two) - Increases damage by 50% and disorients target for 2 seconds.
Blight (Base Skill) - Liquidize your targets' internal organs for 8 seconds. Deals increased damage as targets' health decreases up to 300%. DoT/Execute, 24m range.
Blemish (Morph One) - Reduces targets' healing received by 20%.
Impair - (Morph Two) Snares target by 40% for 8 seconds. Costs Stamina.
Paralyze (Base Skill) - Immobilizes targets in a 6 meter radius for 4 seconds and deals damage. AoE root.
Major Paralytic (Morph One) - Snares targets by 60% for 2 seconds after effect ends.
Mass Maim (Morph Two) - Snares targets by 20% and deals heavy damage over 6 seconds. (The root is no longer applied here, as the DoT is meant to deal much more damage than the initial cast.)
Soul Siphon (Base Skill) - Deal damage to target and steals their health over 8 seconds. DoT/HoT, 24m range.
Resource Siphon (Morph One) - Instead of healing, restore 150% of damage done as stamina and magicka when effect ends.
Soul Blast (Morph Two) - Instantly deal damage to target, also increase damage done by 20%.
Major Defile (Base Skill) - Summon a rune that deals damage to all enemies in area. Ground placed AoE/DoT. 20m range.
Cursed Defile (Morph One) - If an enemy leaves the area they receive all potential damage at once, does not include critical hits.
Major Degrade (Morph Two) - Reduce enemy damage inside the area by 25%.
Passives
Refund - If an enemy purges an effect cast by player, 25%/50% of the resource cost to cast it is returned.
Degradation - Increased all DoT damage by 10%/20%.
Skill Ebb - The cost of Defile skills is reduced by 30%/60% if a Defile ability kills
the target, for 6 seconds.
Life Steal - Dealing damage to enemies with Defile skills heals player for 1% of
maximum health.
Necromancy Skill Tree
Ultimate
Summon Bone Colossus (Base Skill) - Summons a skeletal colossus for 20 seconds dealing heavy damage to all enemies in a 6m radius and stunning them for 2 seconds on cast. (Works just like a Storm Atronach. However it is mobile and will chase down people and bash their heads in.)
Summon Lich (Morph One) - Summons a Lich from the Soul Cairn dealing massive damage to a target of your choosing. (Basically a Storm Atronach that attacks who you want with the Soul Assault ultimate, it cannot be stunned or interrupted and the attack only ceases if the Lich is killed, caster changes the target. Or the enemy being targeted dies/purges. No longer stuns on cast, but it is immobile and ground placed. Useful for taking out Emperors' or other beefy targets. Lasts 20 seconds. Think of it as a artillery piece.)
Summon Flesh Atronach (Morph Two) - Summons a Flesh Atronach, all enemies hit by it are cursed, and take 50% reduced healing for 8 seconds. When the Atronach dies, it leaves behind a circle of disease for 4 seconds snaring all targets within a 10m radius by 70%. (No longer has stun on cast, but lasts 30 seconds instead of 20, also attacks target of your choosing. So it isn't immobile.)
Summon Skeleton (Base Skill) - Summons a skeletal pet that attacks a target of your choosing. (Works just like Clannfear/Familiar)
Summon Poisonous Skeleton (Morph One) - Skeleton explodes when it is killed dealing massive damage to all targets within 8m and afflicting them with a DoT that lasts 6 seconds.
Summon Flaming Skeletons (Morph Two) - Summons two skeletons that deal less initial damage but put a strong DoT on target.
Summon Zombie (Base Skill) - Summons a zombie that attacks a target of your choosing.
Summon Wraith (Morph One) - Summon a wraith from the Soul Cairn that deals frost damage to target of your choosing. (Hits relatively hard, like Crystal Shard damage. But it's ranged, can be reflected or dodged. Dies pretty quickly.)
Summon Ayleid Spirit (Morph Two) - Summons an Ayleid Spirit from the grave that buffs you and your allies until defeated. (Relatively beefy, heals well, does not heal itself, but you can heal it.)
Cursed (Base Skill) - Curse the target increasing all further damage to target by 10% for 60 seconds. 24m range.
Enhanced Curse (Morph One) - Target has recovery rates reduced by 50%.
Annihilating Curse (Morph Two) - All attacks against target deal 20% more damage.
Bone Armor (Base Skill) - Encase yourself in the bones of your enemies increasing maximum armor. (Basically Sorcerer skill.)
Bone Shroud (Morph One) - Increases spell resist as well.
Cursed Armor (Morph Two) - Cast again to deal massive damage to all enemies surrounding you and reducing their healing received by 10% for 6 seconds. AoE, 8m range.
Decompose (Base Skill) - Afflict the target dealing damage over 8 seconds. DoT, 24m range.
Heightened Degeneration (Morph One) - Deals 100% more damage.
Perishing Effects (Morph Two) - Target's recovery rates are reduced by 20% and target is snared by 20%.
Passives
Undead Resistance - Pets take 20%/40% less damage from all attacks, Ultimate included.
Master Summoner - All pets deal 10%/20% more damage, Ultimate included.
Plague - Decompose and morphs have a 50%/100% chance to stagger the target for 2/4 seconds.
Master Necromancer - 2%/5% chance if enemy purges an effect they take absurd amount of damage. (Like 40% of a 25k health pool damage.)
Cursed Magic Skill Tree
Ultimate
Well of Blood (Base Skill) - Summon a pool of blood healing all allies within over 10 seconds. 10m radius. (Drops on top of you like Standard/Veil. Nowhere near as powerful as Templar Remembrance but same idea.)
Well of Suffering (Morph One) - Removes heal effect, instead, all enemies that enter effect take damage over time and are snared by 70% for the duration of the effect. Snare and DoT do not end if they leave the effect. (Meaning if you walk into it, you can't just leave it to avoid the damage or snare, you can however purge it.)
Well of the Profane (Morph Two) - Increased duration to 14 seconds and reduces damage taken while in the area by 10%. AoE Heal. (Basically Templar Remembrance, only longer, and not as powerful in the heal department.)
Shackle (Base Skill) - Shackles your target in torment, immobilizing them for 4 seconds. Root, 24m range. 1.5 second cast time. (Bypasses block.)
Tainted Shackles (Morph One) - Deals damage over time.
Suppressed Shackles - When effect ends target is snared by 70% for 2 seconds.
Dark Spear (Base Skill) - Charge to a target and deal damage to them, if target is stunned/immobile/feared/disoriented/off-balance, damage is increased by 200%. 4-24m range.
Cruel Strike (Morph One) - Snares the target by 20% and inflicts bleed for 6 seconds. Costs Stamina.
Diseased Spears (Morph Two) - Attacks the target twice in quick succession for massive damage and reduces healing received by 20% for 8 seconds. Ranged reduced to 8m. (Basically Templar Puncturing Strikes with a twist, and higher cost, higher damage, and debuff. No longer acts as a gap-closer ability.)
Consume (Base Skill) - Consume the target, dealing damage and stunning them. 6m range. High damage.
Deadly Consume (Morph One) - Applies a DoT that if purged, explodes dealing damage.
Devour (Morph Two) - Devour the target with magic, restoring health and stamina. Channeled for 4 seconds, restores up to 20% of max stamina and 40% of max health. (Deals no damage, instead, acts like vampire ability, Drain Essence.)
Poison Cloud (Base Skill) - Summon a cloud of poison that deals damage to all enemies in it's area for 4 seconds. 6m radius, AoE/DoT. Ground placed.
Poison Eruption (Morph One) - Cloud explodes on cast dealing more damage.
Prolonged Exposure (Morph Two) - Duration increased to 8 seconds, radius increased to 8m. Longer you stand in it, more damage you take.
Spectral Shroud (Base Skill) - As you take damage, gain back 2% of incoming damage as Magicka and Stamina. Lasts 20 seconds or until recast.
Spectral Armor (Morph One) - When recast, all incoming damage received is converted into a damage shield for 6 seconds. Shield caps at 60% max Health.
Spectral Boon (Morph Two) - Increase Health recovery by 60% while active. Cast again to heal yourself for 50% of damage received during the effect.
Passives
Utility Healer - Increases healing done by 3%/6%.
Alchemist Master - Increases Poison and Disease damage by 5/10%.
Necromancer's Boon - When activating a Cursed Magic skill, gain 2%/5% magicka. (Acts like Dragonknight's Earthen Heart passive.)
Spearman - Increases damage with Dark Spears and morphs by 5%/10%
The reason for the insane amount of DoTs and debuffs with this class, was really, because you can purge everything, so while the build remains effective, it doesn't work well in PvP with people with brains. Which is why one of the passives has a small chance so that when you purge a Necromancer's debuff, you have a small chance to blow yourself to kingdom come. I'd have to say my favorite abilities in the entire thingy ma jig I came up with have to be the Lich ultimate, and Blight, Lich ultimate for self-explanatory reasons and the Blight ability because my sick mind and that awesome description makes me smile.