This is a pretty standard control shell with the typical Restoration Angel combos and the addition of Archangel Avacyn as a win condition. Though the cards included in this list seem fairly common, control isn't in this format, so I'll dissect the deck the best I can.
CREATURES:
Wall of Omens - This stagnant card may seem underwhelming, but it's exactly what we want early game. It draws us a card, blocks early threats, doesn't die to Lightning Bolt, and is also a target for our angel.
automatic playset
Kitchen Finks - If you've played against this card you don't need me to tell you how good it is. This, too, is exactly what we want in an aggressive format. Obviously this combos nicely with Restoration Angel, allowing us to gain life and remove the counter from the finks.
automatic playset
Restoration Angel - Flash, flying, and a bigger butt than three, what more can a control deck ask for? Aside from being a great beater on it's own, Retoration Angel combos nicely with the previously discussed cards.
3-4
Archangel Avacyn - The nameholder and flavor of the deck. Avacyn is not only a great beater, she's also a good control card giving our creatures indestructible and us a possible board wipe.
1-2
INTANTS:
Path to Exile - This is the premier removal card in modern. It gets rid of everything including those pesky Tarmogoyfs, so play four.
automatic playset
Spell Snare - This is one of those cards that you have to test to truly appreciate. I can confidently say that this is the best counterspell in modern. This counters Tarmogoyf, Eidolon of the Great Revel, Mana Leak, Terminate, Lightning Helix, Skullcrack, Scavenging Ooze, Remand, Thalia, Dark Confidant, both merfolk lords, Archbound Ravager, Steel Ovetseer, etc etc etc; you get the idea.
2-4
Condemn - If I made a list of the most underrated cards in modern, this card would have to be in the top five. This deals with Tarmogoyf and disrupts aggro's early game for one mana. Why not?
0-2
Mana Leak - The best two cost counterspell in modern. With aggro decks running the show in modern, the chances of our opponent having three additional mana to cast their spells is pretty unlikely, making Mana Leak essentially Counterspell.
2-4
Crpytic Command - So you want an answer to any situation late game? Well this is it! This card has lost a bit of popularity recently, but I'm still a firm believer in countering a spell while drawing one, or returning a land to a starving opponent's hand after drawing the answer I need to what they managed to get onto the field.
2-4
SORCERIES:
Supreme Verdict - A boardwipe that can't be countered; seems pretty good. With decks like Affinity, Merfolk, Zoo, and Zoo with Lava Spike running rampant, someone needs to instill some order. What's a better way to do that than killing everything? Nothing gets it done like Supreme Verdict.
1-3
ENCHANTMENTS:
Detention Sphere - We don't run a lot of removal, so having a card that possibly deals with multiple threats is appreciated. Lingering Souls tokens are the greatest targets for sphere, but this card hits pretty much anything. Consider it our slightly worse Maelstrom Pulse.
0-2
I'm not going to go over the lands since those seem pretty obvious; run four Celestial Colonnades and around twenty-one to twenty-three other W/B lands. However, I will go over some cards I don't run and why.
Remand - While I do really like this card (paying two mana to end our opponents turn and drawing a card is great), I find that "killing" our opponent's spell is more important for a control deck.
Ancestral Visions - This card is great on your first turn, but any turn after that it's just awful. I have died more times with this card in suspend than I've seen it resolve. It's also the worst topdeck possible.
Snapcaster Mage - I don't run him for one simple reason: the mana curve. I already run enough two costs in this deck, running snapcaster alongside Wall of Omens is a mistake. If this deck wasn't playing Restoration Angel and friends, then I'd easily run a playset; but alas, that is not the case.
Serum Visions - I honestly don't understand why some people run this in their control deck; we don't want to be controlling our side of the board early game (that's combo's role), we want to be controlling our opponent's board. I think that people include this in their control deck with Splinter Twin builds in mind not realizing that Twin ran it for its combo. I'd rather save mana for a Spell Snare than set up my next two turns.
