zipec

My thoughts:
1. You need more creatures - not that many spells that pull creatures out. You need synergy with my favourite Lolteth troll. :-)
2. Varolz seems awesome in grave loving decks
3. Do you realise Grim Return says "From the battlefield"? Therefore I dont like it here.
4. Drop Elixirs. You should be fine, you will not deck yourself.
A bit of work and this will be nice deck.

You can cast instants before or after an effect resolves, never while it is resolving. To put it in example: When an effect says "draw a card then discard a card" like Desolate Lighthouse, you can NOT cast a spell in between draw and discard, because its a part of resolution of the single ability. Same with Vexing Devil: You can cast instant before your opponents decide or after the Devil is sacrificed (assuming he payed 4 life). Because its all single ability.
I hope its clear now.

Why all the hate when you also see that this deck has several problems? I acknowledge my comment was too generic but I hoped that brief feedback is better than none.

I will try to be more constructive this time:
1. I strongly discourage you from using Commanders Authority and Heavy Mattock. They are far too expensive for what they do. (the bad cards I mentioned)
2. Choosing a theme (Avacyns Vengeance) is a nice first step, but you have to clarify the second step: chose a strategy. Do you want to overwhel your opponent with tokens? Or fly over his defenses while crippling his forces? Or do you want to command several powerfull angels to beat him? It can be anythimg but it should be clear. Think about it, decide and then rebuild the deck according to the new plan.
3. For the deck as is(if you dont make many changes) the first you can do to help is add 3-5 lands.

I hope this helps, If you rebuild the deck, just add comment here and I can supply more ideas.

Too many pieces of combo. You need High Tide, Cloud of Faeries, some bounce, cantrips. Honestly I cant even think about best case scenario. Dependant on draw, cant run infinite if I am not mistaken. Also I canr see your win condition, is it Kaerveks Torch? How exactly do you generate enough mana?
Maybe I just dont get it but from all the combo decks I have seen this one seems too fragile or even flawed.

Gaining life is nice and all, but you should use it more. Sure you have Archangel of Thune and Voracious Wurm, but in lifegain-centric deck like this Angelic Accord also sounds good.
Also you may want more lands.
All around not bad, but I dont like how expensive it is :-)

Did anyone actually let the first 4 damage to himself and not the second? That is huge misplay. Its either 8 damage or 4/3 beater. Still not bad for turn two and 2 used cards.

No, you cant do anything in response to their choice because its a part of resolution of single triggered ability. So you have to give it undying before the ETB trigger resolves.

Most of your changes are fine. I dont like only Grixis Charm because it is not standard-legal. From other spells, check Teleportal, but another unblockable may be redundant.

What exactly is the use of Punishing Fire here? And why are you splashing green just for Firespout? Isnt it easier to just run Slagstorm?
Also your wallet will pop from Remand+Spellskite+Kiki. Since you use Preordain and Ponder I assume this is not modern tournament deck so you can go easy with something like Rune Snag or Memory Lapse instead of Remand.
Also I warn you, this is a competitive combo so your friend might stop playing with you. :-) That happened to me when I constructed Painter-Stone deck :-)

This looks like a limited deck. Did you actually just tear up a few boosters and built this? :-) You use a lot of cards that are mediocre at best or just plainly bad. Also cut the Sunlance and you have Standard legal deck :-)

Not bad for a budget. I see what you are aiming at. You can also try soulbonders like Wingcrafter and/or Tandem Lookout.
Only Archeomancer and Corrupt seems a bit out of place here.

My thoughts:
Would be nice if Utopia Sprawl could be in place of Fertile Ground, 1 less mana would speed you up awesomely. But the fixing is worse. Both are better than Farseek for sure (Ethereal Armor all the way :-) ), although more vulnerable to land destruction. But Umbra Mystic can help it.
Imho, the land mana-colors are distributed better now. (W:14,G:15,U:12)
I am sad with Noble Heirarch to Birds of Paradise change, but I understand budget reasons behind it.

But there is nothing to complain about. Looks really good.

Also maybe Mortify instead of O-Ring. Instant speed, no drawback, and you only miss artifacts. But it depends how much you want to be dependent on Black (as for now, only Sorin needs it for his cast, Souls and Vault can be used to some degree even without black). Or maybe unmake? Stricter targeting restriction, but it exiles.

Godless Shrine instead of Fetid Heath maybe? Its cheaper.

It is out of color. I wouldn't splash green just for Doubling Season or Parallel Lives (better here, cheaper) although they would work.

@xxsupernova103xx: How many copies do you run exactly? Last time I checked, there was none.
(To explain: I didnt say it can't be handeled, I just said you have no answer. You can slow him down only by siding Sundering Growth)

Wow, I thought this deck lacked some strong enchantments (e.g. Unflinching Courage, Spectral Flight) to be good and Boros could truly beat it, but then I saw what you posted...
I wonder how you defend against:
T1: Gladecover Scout
T2: Rancor + Ethereal Armor
T3: (here is where Unflinching Courage should have been) But Curiosity and second Ethereal Armor will suffice
My point is, your deck is slower.

20 lands, no ramp, and you run Sorin Markov and Sorin's Vengeance? It will not work.
If you want to play Sorin, look at this article http://www.wizards.com/magic/magazine/Article.aspx?x=mtg/daily/boab/200 Well bulit Sorin control, explained and described how to play it.
If you want to play vampire aggro, just drop these two cards. Also quite nice vampire aggro 10-or-less deck I saw here: http://www.mtgvault.com/cinzano/decks/10-or-less/

Also about the manabase:
I like hierarch a lot, expensive but awesome, in bant auras better than Birds of Paradise for sure.
But I dont like Farseek.
Your lands produce: W:12 G:16 U:13
Your spells consume: W:32 G:15 U:14
Maybe if you focused your lands more into white, you would not need Farseek for fixing. I am not sure, but you can try it.

Not bad, but few small points:
1.If this should have been modern, maybe you wanted Unflinching Courage instead of Armadillo Cloak.
2.Instead of Oblivion Ring you can run Detention Sphere. But the ring is fine I guess.
3.Also I dont like Jenara much, maybe Aura Gnarlid fills the same role? Kinda - evasive, continually growing creature :-)
4.Steel of the Godhead is arguably the worste enchantment you have(3CMC,conditional), fits nice with Geist, but otherwise I would play less copies in favour of other enchantments.
5.Try Daybreak Coronet and Invisible Stalker
6.Fertile ground may be better match to Ethereal armor than Farseek although more vulnerable.
I play modern UW auras and I am still looking for improvements, if you want some inspiration or possibly help me a bit I would be glad. http://www.mtgvault.com/zipec/decks/uw-crowned-bogle-modern/