Well, since I've got to head to class in a moment and taking the time to ready all that is written here as well as looking up how energy works (honestly never used an energy champion so wasn't sure how it worked), I've got time for a quick couple of notes.
I like that you tied your champion in with another from the League. It's something Katsuni recommended I do with my champion (which I'm currently working on a rework of my lore) and I happy to see you did such the same. On that note however, I've got a couple of issues.
1. When you first said "her" in your second paragraph, I was confused momentarily as you never mentioned the *** of his beloved instructor. I would consider rewording this or mentioning earlier that this instructor is female.
2. While I like how Lee Sin is used, I cannot see him murdering this instructor for no reason after reading his lore. He may have very well taken in an apprentice (granted they didn't get in his way) in his years studying to be a summoner. If you stick with Lee Sin killing her, it would be nice if a reason was given, even if Vindictam doesn't know the reason and is following a large misunderstanding. Another angle you could go at is that his instructor was in the village that Lee Sin accidentally destroyed during his expirimental summoning (mentioned in his lore). She could have been visiting there and got caught up in it. That would give Lee Sin to feel guilt (like in his quote you placed) as well as give Vindictam his reason for wanting vengeance on Lee Sin. Again, these are just examples.
A note on the abilities. There is a lot of debuffing here and it gets quite powerful when all stacked with each other. That being said, I don't currently have the time to balance numbers and compare them to other champions, but from a quick look, he can reduce 60% of their damage, 40% of their defence and slow them for 25% (for an unspecified amount of time) all at once. Each of these abilities have damage and cannot be dogded by the opponent as they are not skill shots, but targeted abilities. So this seems very powerful as you can burst in with all three abilities with 160 of your 200 energy (given you have the standard max energy). With runes or waiting till one is off cooldown, you'll already have enough to toss out any one of the three abilities again (like to slow to get away). Not only is this devastating to the oppenent from just you, but imagine if you had a teammate to take advantage of the situation....
On the ultimate, I'll most likely have to look over again when I have more time. Here are a couple of notes on first glance.
1. First glance of the cost 100 is half of 200, seems high as the there are only two other energy abilities that cost such. Those being Akali's Twilight Shroud 80-60 energy, and Shen's Shadow Dash 120 energy.
2. Second glance at the cost compared to the insane range of the displacement, it seems like it's too low.
3. Blitzcranks grab only has a range of 975 and only dispaces the enemy towards himself, while you have given Vindictam a 1000 range radius around where the enemy is to be displaced in any direction.
4. Because of the above, and that energy is a regenerating source, it'd be hard to factor in the cost, but a 2 min cooldown for that type of utility is a little low in my opinion and I would consider increasing it.
All in all, I did enjoy the lore and the Ultimate was something I've not seen before (well displacement used in that way at least).