Best character award goes to Cato* Echo! Please report to the M:EM immediately.
Okay, the card. The +1's pretty cool, but it doesn't actually do much. It's quite the setup for the -2 though. If an opponent wants to race you, they better take care of Selvira before you can activate her -2 a couple times. Still, on an empty field both abilities are kind of pointless. Not bad if some abilities are rendered moot, but all Selvira can do with an empty field is slowly build up. Looks like she found her immortality with the -6.
*I blame the shared c sounds and o-ending in both your names.

So many black/white walkers here. It's a popular colour combo!
Repeatable discard is usually pretty scary, but if it only hits one card type it's probably alright, even if that's the only card type most decks can use to take out your discard engine. Mechanically this seems pretty sound. My only mechanical concern is that the life condition on the emblem might make for some boring games. If you have more life than an opponent and activate the ability, you've effectively won but the game can continue on. Most players would concede, but you just know there's that one guy who's going to drag the match out, never actually attacking you for fear of dying.
Flavourfully I never really like walkers that ignite midway through the story after meeting the protagonist. With the odds of a random person being a walker and their spark igniting being about one in a trillion* it always seems a little too coincidental. Really the only reason walkers would ever meet is if their personal motivations bring them into contact with one another.
*One in a million has a spark, one in a million of those ignite. Seems stupid to me too, but it's canon.

Interesting character. I've never even considered a Nightstalker planeswalker before.
I like how the ultimate ties in with both the + and - abilities in different ways. Both abilities also give you something useful to do regardless of what situation you find yourself in. Very nice. Nothing about the card seems overpowered either. ONly real flaw is the lack of means to protect itself.

Oh god, I love this guy*. His motives, such as they are, are especially interesting. Does he think the unexplained phenomena will bring down Elori's religion? Maybe he's trying to help out... somebody? Nobody knows. I imagine his reasoning for what he does changes on an irregular basis.
The +2 outside of certain deck types only exists to power up the ult. Since powering him up only to risk Krolf getting attacked is a bit of a gamble, I'd prefer to see a little more value out of the + ability. A weak + ability on a 3 cost walker is totally permissible however.
The first 0 is powerful, but also a likely one way trip to the graveyard so it works out.
The second 0 is pretty interesting. I need some clarification on what "You may cast instant and sorcery cards exiled this way, but no more than ~'s loyalty" means. Can you only cast a number of cards equal to his loyalty? Converted mana costs equal to or less than his loyalty? Does every card played count towards the limit, or can you play any number of cards as long as they meet the criteria? Are you still playing with Krolf from exile? That seems like a simple way to keep track of counters?
It's also cool how the crazy guy has a + and two 0 abilities and tends to kill himself off. I don't worry about this guy wrecking standard (he's probably needed to deal with Tarmogoyf), but I wonder if he has legacy potential too.
*Making an assumption here, but "krolf" just sounds like a masculine name.

Obviously the best card. Easy choice. No contest.
I actually really like the +2. It's rather interesting. With that as a +2 though, I worry her loyalty may get out of hand.
The -X works well too. I wouldn't pay to deal four damage, or in most cases to get 4 1/1s. Together though, they're worth the price of admission, especially if you can pump he up first. If you just need a single blocker to buy another turn Zakon can oblige you there too.
The ultimate is both boring and lacks synergy. If this wins the vote I'd probably replace it entirely.
In play Zakon is really, really good at keeping you alive. Between plentiful chump blockers and an ability that could take down even the biggest creature, or at least force your opponent to waste creatures if they want to attack and finally a hefty 4 loyalty (probably six by the time your opponent goes) the lady does not go down easy. Great for bleed decks I suppose.

Concept: Interplanar bad guy hunter with morals? I mean, he sort of feels less black the moment he rejects the job, but I suppose love can be a selfish desire? He's okay. Doesn't make me feel giddy, but no feelings of aversion either.
Goal: Impress Aloise? I'm not one to oppose unrequited love. I don't like how he seemingly trashes his job though, it de-emphasizes his capabilities.
Card: That's like 5 abilities you've got there brah. Carefully with the text box, it's on a diet. He's also mechanically not that black, can't uptick on an empty board, provides little interactions despite a hefty mana cost, and various other equally minor things that sum up to something I'm not too fond of.

Concept: Vampire Vedalken Planeswalker that is too much of a chump to give her husband a proper death.
Goal: None.
Card: Can't say I feel much vampire. And the ultimate is sort of "whuh" and "meh" at the same time.

Concept: I sort of like it, but I need more flesh on his immortal bones.
Goal: I can't see him not becoming an antagonist in the later arks, but that's okay.
Card: You're tired of this by now, but I'll still reiterate that the 0 is bonkers. He also doesn't promote very interesting play decisions, and his ultimate is really boring.

Concept: I feel he loses out a lot by being called a vampire, rid him of the compulsion and just let him suck the lifespan out of people, which he needs to do to regress his own age. Right now he's a time thief + vampire when he feels like it, which is a little disjointed, unnecessary and weird.
Goal: Uhhh. This whole "he's bound here because" irks me the wrong way. I feel there could be a more compelling and elegant method of forcing him to stay. Range of power connected to a location maybe? I dunno.
Card: Why does the controller gain 1 life? Why does the second ability make every creature leech off all lifegain? Why isn't the ultimate worded for multiplayer? More seriously, I sort of like the first ability, not counting the random life gain. I don't like the second one, and the third one should totally (aside from being targeted) be worded "Your life total becomes 19".

Concept: I like it. That's all.
Goal: It's a little weak. "Uhm, moon, reverse time sort of, dying of age, eh let's go with it." I don't think this moonrise project will come from going back in time to where there was a moon, but feel free to prove me wrong. I've heard that F&S loves time travel stories.
Card: Personality wise, she sounds a little blue, believing that understanding of an element can help solve it. Mechanically, she doesn't feel right. She's very violent, when she seems more like a support character. Discard effects are a little out there, mostly. The first one can sort of be justified as blood magic. It's a pretty bad +1 though, all things considered. Ultimate is sort of cool, but has way too many abilities. Condense it a little.

Concept: Why is he black, if I may ask? I get that black has underlings at times, but they are at least usually oppressed by someone else selfish. I don't think gratitude is a word in the black dictionary.
Goal: Feels like a side-character that you could write shounen about. I'm not sure if I like or dislike that he's a little disconnected, but the tenuous connection with Aloise is sort of neat.
Card: Really hard to catch up against, protects himself a little too well. I don't get his ultimate.

Concept: Nightstalkers is cheating, they are way cool. He feels a little, and I don't particularly like using this word, "edgy".
Goal: "Whatever suits the day" is a little on the weak side, imho. He's too flexible, he doesn't feel like he has any weight behind his actions.
Card: The abilities are a little disjointed, and the +1 is really good.

Impeccable, COTY material

Concept: Ah man, brainwashed zealots are the best, although I'd argue they're in RW territory. Well, they're mostly just W, but R sort of leads actions to their motives. I like characters that represents a greater whole.
Goal: Ya blew it. Here I hoped she would erase every trace that hinted at her not being special.
Card: bretty gud. A little heavy on the X's.