You have your Angelic Walls there as your first line of defense. If you have none of those in hand then you can start your T:2 with a Heartless Summoning and then proceed to lay out your big creatures.
Throw down a Palisade Giant and pop a Indestructibility on it and your all but golden for the game as long as you mind your step and don't take a Tragic Slip
Did Heartless Summoning -1/-1's weaken your creatures too much to contend with your opponent? Ajani and Ethereal Armor can buff them back up.
Not drawing the right cards or have already lost some important ones? Underworld Connections will help with card draw and Treasury Thrull can get your creatures or enchantments back.
Lost some life before you got your defenses up? Get some of it back with Lifesteal from Angelic Skirmisher or Vault of the Archangel.
If you are really lucky and have your 2 Heartless Summonings out, you can have your Avacyn, Angel of Hope out on turn 4.
Sideboard is mostly focused on defense for Control decks. Guardian of the Gateless can swap out Seraph of the Sword if your opponent is swarming you.
I set out to build a deck that is based around Heartless Summoning to allow you to get the big creatures out fast while being able make those creatures very difficult to get rid of. I left out O-Ring from my list of Enchantments because I feel that the biggest threat to this deck is heavy control and O-Ring does not help with counters or Supreme Verdict. I also left out some cards that might fit well such as Griselbrand because I do not have any and I did not want to spend the money on cards that will rotate in a month. If I left something out or you have any ideas on how to improve the deck and make it viable please let me know. Thanks for taking a look.