(A long description. Skip to the 3rd paragraph to get to the nitty gritty if it pleases you. For those more interested in LifeGain decks, please read, enjoy, and your comments/suggestions are always appreciated!)
The problem with life gain/felidar sovereign strategy is the fact that he takes 4WW (6) to get him out on the board. Based on your hand, your mana pool, how fast your opponent is building momentum, and if you even HAVE a Felidar on hand, you will usually get the crap kicked out of you by the time you pull one. Thus this strategy alone sucks. It took me forever to figure out why it was sucking so badly and why life gain couldn't be more formidable than just casual play. I was so intrigued by Felidar Sovereign that I tried many many test runs on a decent versatile lifegain deck. It just didn't work. If my creatures blocking were destroyed, my precious life would be hacked into nothing shortly after. If I had no creatures to play, I'd gain life in hopes of stopping my opponent's strategies with some white-control cards such as Path to Exile, effectively just prolonging my demise with such outrageous lifegain.
Every card in your deck must be something useful. Having a hand with a few cards that don't to anything until you pull a card is a few cards too many. The cards' abilities alone should stand up independently, and should combine with other cards for optional combos.
Defenders: these cards were part of the question and their voices were answered with the release of the numerous defenders found in ROE. A major example would be Worldwake's "Perimeter Captain." Coupled with other defender cards with their own useful abilities, you could gain life and do other neat things. "Wall of Omens" with a "Eland Umbra" becomes a 0/8 Totem Armor Wall that allowed you to previously draw a card. "Stalwart Shield Bearers" beefs your defenders up even more. These defenders act as your perimeter effectively defending your turtling strategy.
Life-Gaining Creatures: There are a few ways to do this. I chose the "Lone Missionary" simply because he's fast to get out, you gain 4 life when he comes onto the board, and he's a 2/1. He is the sacrificial lamb. Use him only to block; it's useless to use him to attack unless your opponent has no creatures on the board. I could have gone the Kor Soldier way and put a bunch of "Soul's Attendants" and "Conquerors Pledge" as well as "Nomad's Assembly." (There are other cards like this as well). The problem lies with their high mana cost and sacrificing time for mediocre lifegain.
Lone Missionary solves the problem by being a creature and an effective lifegain spell. "Souls Attendant" however, still has it's uses and is placed into the sideboard. It does, after all, allow you life gain for both yours and your opponents creatures. Perimeter Captain's as well as all your other defenders help push you little by little as well and fend off repeated attacks.
Control: This is the most important part. The sideboard is mostly for your control. "Celestial Purges" "Demystify" and other such cards can be placed here. Your standard set up should be x4 "Path to Exile" and x4 "Journey to Nowhere." I placed two "Day of Judgment" in my deck. When faced with an opponent building up an army of beat-stick creatures, and your putting up a wall of say 4-5 creatures, some with defender. Play any cards that might be useful, and then "Day of Judgment" everything. The best combination for this is to place any Totem Armor cards on some of your creatures. You'll be left with part of your wall of creatures still standing after the dust has settled. Depending on your life, hopefully you've held off on any felidar sovereigns you've pulled, nows the time to unleash your game changer. This is where the two "backup plan" cards may come into play. "Nomads Assembly" and "Conqueror's Pledge" are strange cards to put in this deck but after a wipe from a "Day of Judgment" it's fast creatures. Nomad's amazing rebound ability is icing on the cake. "Brave the Elements" are placed for extra defense. You definitely want to save "Path to Exile" for big creatures like eldrazis and other such threats. Leveler creatures always need to go. Eldrazi Spawn can be burned by a "Day of Judgment" or just wait until your opponent pops them for bigger creatures and then exile them. Keep the game going.
Gideon Jura: The idea of this card is just outrageous. I don't know if I'd ever spend the money on him, but if you know what he does, his abilities are obviously useful here. On a budget? Forget him. Which is why he is side-boarded.
It is a strange strategy and I will probably constantly tweak it, like a chemist searching for just the right formula. I think I find lifegain one of the most interesting strategies: how to win by dealing little damage. I've tested it out on a few other standard decks and it holds up well. It's versatile and certainly a fun deck to play. Thanks for reading! Any comments or suggestions would always be appreciated!