ToME: the Tales of Maj'Eyal

I've found Shadow Veil had great potential, full immunity and 30% damage reduction for 8 turns, pairs with Meta, and Draconic Will, you've got yourself a character that's completely immune to debuff every turn. So i've tried to build around it, and after trial and error, this is the one, well, at least beating Nightmare in a breath:

The only problem for Shadow Veil is you don't get to control yourself for 8 turns, so making sure not die from it is what matters the most:

Race: Ogre
For staff+ shield, and four enhanced inscriptions. Shortstaff could work without Ogre, but it is a pain to find one, and definitely not early in game.

Class talents:
1. Ambuscade: Shadow Veil

2. Meta: remove magic effect & 30% CD reduction

3. Demon pack: This one skill carries your defense,offense and survival
Offense: firebolts/Corrosive Cone works better than Magic Combat, Corrosive Slashes/Corrosive Cone turns everything into acid damage even in Shadow Veil, plus 65 armorpen. No joke. And you can always switch imps without taking a turn!
Defense: Bloodshield, flat all damage reduction.
Survival: Fiery Cleansing, best status removal in game, hands down. Plus 8% vamp and a teleport.

4. Rampage: a free movement, some damage reduction and attack speed, nice. You are always able to run away from a fight, which is a big deal for early game.

5. Temporal: Time shield, 45% global speed(speed does count in Shadow Veil, you can blink on multiple foes per turn if fast enough, unlike what SV is described).

6. Bone: prevent from being one shot out of LOS, and with all the damage reduction skills, Bone shield can actually block the real hits. Crucial for Shadow Veil.

7. Absorption: more damage reduction and TK weapon.

8. Sun: Early game Sun Ray, best mobility skill Path of the Sun, 10% critical for both physical and magic, Sunloak provides 37% more CD reduction(that's 67% pairs with Meta), everything refreshes after Shadow Veil.

Generic Talents:
Light/Aegis: the defense of an Archmage
Energy: 30% damage reduction, put foe's talent on CD, sustain removal all in range 10.
Buy Staff Combat

More candidates:
Stealth: auto critical such early in game for skills like Sunray and Barrier makes difference.
Demonic Strength: debuff on hit, more critic, heal, damage boost, damage reduction, what's not to like?
Time Travel: spells cover early game(3 cd 10 range, much better than Sunray), utilities like locking foe away for 8 turns or transport to a safe place for 7 turns is also incredible useful. And the last one is a great finisher.

Stats:
Magic>Cun>Will
You want your TK weapon to hit, so Staff is the obvious choice here.

Prodigy:
Hidden resource / Draconic Will

Inscriptions:
Teleport later switch to phase door(65% all resist, 65 defence and 65% debuff reduction, 7 cd 7 duration)
Shield
Manasurge later switch to movement or a 2nd shield(before hidden resource, manacrash can destroy you.)
Wild later switch to Heroism

Sum up, here's the combo loop:
Step 1. Hidden resource, Precognition(escort) to make sure you're not diving into something too crazy(like tons of mage rares plus bone giants), then Sunloak, most of your skills and runes will only have 6-7 CD now, cast all the shields/buffs, turn blood shield on, Rampage, at last Shadow Veil.
Step 2. 8 turns after, everything refreshes except Hidden resource & Sunloak, pop Draconic Will to cover 5 turns, alternative can be time shield + phase door(easily 90% debuff time reduction for an Ogre), and then do step 1 again, this theoretically goes infinite. But usually one cast will just clear a full vault of foes in a blink of second(And that's why we play this guy).

Notes:
1. This build doesn't provide resistance penetration from talents, but you can switch your damage type pretty easily by switching imps. Corrosive Slashes/Corrosive Cone for 100% Acid, firebolts/Corrosive Cone for fire, dark & acid.
2. Since shadow Veil can't target, a necromancer boss can be a pain in the ass. So be prepared before fight.
3. I first intended to build sacrifice into this build, but 2 category points for one talent is lame, and the resource management is too painful before Hidden resource. That's when I decided to go for damage reduction + shielding. Blood shield/ Energy Decomposition/ Absorption/ Rampage/ Shadow Veil/ Bone Shield/ Shield runes/ Barrier/ Aegis looks pretty solid.