I found that IGN has developed a little character builder and tried it out. The goal of the character is something of a Mage Assassin, combining Illusion, Conjuration, and Enchanting with Sneak, Light Armor, One-Handed, Archery, and Smithing. This is a level 81 build and I decided to focus on the heavy armor smithing for the weapons plus Dragon Smithing to put points towards Conjuration and One-Handed. I like Dunmer Male's looks the best for this type of character simply from a role playing perspective. Here is the build:

http://www.ign.com/builds/the-elder-scrolls-5-skyrim?d=00000000000000000010111110011111111100000011110000000000000000000000000000000000001000111001000111111000000000000000000000000005011010321511112300000000000511101511111111

This is the character I believe I will have the most fun with. I know that many would recommend a "pure" assassin for the sake of simplicity, but again this is the kind of character I would find the most fun. I just have three queries:

1. What stat spread and enchantments would you recommend?
2. Any suggestions for which perks to take at which levels? I am horribly OCD when it comes to character builds. I know Sneak for Assassin's Blade is a must early on yet I don't want to sacrifice other skills. I get the feeling I may be in between a rock and a hard place here.
3. What would you change while keeping the core of the concept? Not looking for optimization, just something I'd have fun with but I am open to improvements.

I was intending on very much the same build as yours, illusion and conjuration acts as smoke and mirrors to take the heat off you while you go around backstabbing confused people fighting each other.

However I sort of gotten side-tracked by alchemy (incredibly useful, there is always a potion for any circumstance) and alternation (massive magic resist and absorption passives) and due to the bug with conjuration / magic absorption, it never materialized.

I do not regret my choices as I believe my current build is the most efficient one, especially with the bad hotkey system that gives me fits whenever I want to switch between my dual swords and magic spells. My build lets me just kill and kill without pausing the game.

Anyway, good luck with your sneaky minion master, let us know how it turns out.

You need dark brotherhood gloves for double backstab damage. Other then that, 100 stealth + illusion is enough to do everything. You dont need a single perk in 1 handed or light armor. Smithing and enchanting will make you even more op then you already will be.

My char uses alchemy for +30 damage poisons (at around 40 alchemy)

To answer some of your questions:

1. Sneak don't work well with melee until you have it close to maxed. Use archery until then. Even if you are far away , hitting someone with a sneak attack will give you sneak experience.

2. Smithing makes you a power house. It can be trained without ever leaving the village by spamming iron daggers.

3. Always keep a lookout for smithing and enchanting potions in the shops since you don't take alchemy.

I'm actually going for the same type of class but using an almost enitrely different build.

http://www.ign.com/builds/the-elder-scrolls-5-skyrim?d=0000000000000000001000000000111000000000000000100002100000001110000002101013111100500011100100001111100000000000000000000000000501100030051110100051000100000000051111111000000000000000000001111

I originally had conjuration as a skill, but couldn't justify it with a Mage Assassin. I would sneak around in battle and my thralls would charge on in to soak up damage and in the melee I'd either get noticed or hit the wrong person. I still have plans to raise Conjuration up to 100 and only use a Perma Thrall when things get hairy.

I also had Dual Wielding but again could not justify it as being a spell caster since most of the time I'll always have a spell in atleast one hand, be it healing or alteration, and those perks could fit better elsewhere.

No light armor or heavy armor, with Alteration spells I can acheive 80% melee damage reduction and also have the Atronach perk + sign for 80% spell absorb, and the Bretons daily racial for those oh [censored] moments against spell casters.

The only thing that I am iffy about is deciding between Investing in shops or 100 extra carry weight. Also a little iffy on Stunlocking with Dual-casting. I'd rather not break the game. But I'll decide on how I need to move around perks to become Viable.

I might actually go with this, with a few modifications such as scrapping the Speech perks for some additional One-Handed (Dual Wielding) and Archery perks as well as Assassin's Blade. Is Speech really necessary?

Tried to fit Light Armor in here but I just can't get all the necessary perks. Still, at a certain level I won't even be needing light armor. Still, that Nightingale armor...*drools*

I understand going for both the Dark Brotherhood for the gloves and the College of Winterhold for the Archmage robes are necessary, but what other gear and enchantments would you recommend? Also, how should I be leveling my skills? What perks should I get early on?

EDIT:

Here's my take: http://www.ign.com/builds/the-elder-scrolls-5-skyrim?d=00000000000000000010000000001110000000000000000000000000000011100000021010131111005000111001000111111000000000000000000000000005011010321511101300510001000000000511111111

Anyone have any ideas for allocating my stats or which perks to prioritize? I know Sneak and Illusion are musts but Alteration and Archery also look awesome to level.

I am doing more of a necromancer/assassin hybrid. Fun so far, but I may incorporate elements of your build. Thanks for posting!

I am probably going to forgo Conjuration for Alteration though. Makes sense since I am not using any armor.

I like the general idea of your character....it's kinda similar to what i play so to answer your questions;

Overall late game won't matter so much, early game you will need;

1. Favor health/Magicka equally .... Any 'damage' enchanted bow will be awesome as will be poisons for the arrows
2. The sneaking/Archery perks should be your first priority for survival (You can work on Alchemy etc once you get pas lvl 20 or so)
3. Core concept is fine!

Revised the original build.

http://www.ign.com/builds/the-elder-scrolls-5-skyrim?d=00000000000000000010111110011111111100000011110000000000000010100000021000000000005000111001000001111000000000000000000000000005000000321111112000510001000511101111111111

If it was me, i'd take the one handed and invest the light armor points elsewhere. For your style of play one or the other is enough. Both is overkill. Perhaps look at a little more in Alteration for crowd control when faced with multiple enemies when spotted. The light armor skill wont do much if 5-6 NPC's are attacking you at the same time!

Hmm, possibly. And I do love these robes...

Did another revision. Probably going to allocate skills equally into Sneak, Archery for survivability with some in Illusion for when things get heated and put stats equally into Magicka and Health.

http://www.ign.com/builds/the-elder-scrolls-5-skyrim?d=00000000000000000010111110011111111100000011110000000000000010100000021010131111105000111001000001111000000000000000000000000005000000321111102000510001000000000111111111

This build looks interesting to me. Thinking of going with a stat spread of 20% Magicka, 60% Health, and 20% Stamina or 30% Magicka, 40% Health, and 30% Stamina. Also, is it wise to get rid of Alteration and get Destruction magic perks since I have Illusion or is that wise?