A long time ago I went to a Rise of the Eldrazi booster draft and my deck of choice that I was playing was a
Vent Sentinel
deck. From that point on I loved Defenders because they had potential. And then Return To Ravnica came and with it the beauty that is Axebane Guardian. If you put your faith into this deck you will see that Defenders are 100% broken.
Axebane Guardian, Sylvan Caryatid, and Overgrown Battlement are the engines for the brokenness to commence. They add ridiculous amounts of mana to your mana pool, well Sylvan Caryatid doesn't really it's kind of in here for mana curve.
Red Sun's Zenith is your main win con, all you got to do is place defenders on the field and Axebane Guardian, multiple Axebane Guardians.
Colossus of Akros is an alternate win con that's really easy to pull off in this deck.
Wall of Omens and
Carven Caryatid
allow you to add to your mana pool when one of your main mana producers are on the field while allowing yourself to draw cards at the same time. Originall had Wall of Blossoms in here, but that's not modern legal haha.
Reforge the Soul is in here because this deck top decks very quickly. Using this allows you to constantly get cards to play while possibly screwing up an opponent's strategy that they had in their hand.
Perimeter Captain is fantastic since he will allow you tog gain plenty of life against aggro decks and in combo with Stalwart Shield-Bearers and any number of defenders you control you'll gain a lot of life. To elaborate, with the Shield-Bearers you give your defenders a decent buff and with multiples even more. At that point you can block one creature with every defender you control and with Perimeter Captain gain a lot of life.
Sideboard time! Angelic Wall against decks with flying creatures. Safe Passage in case you're going against a burn deck. Path to Exile because I love that card and you know it's good.
Vent Sentinel
is in here just in case you can't get your bomb for whatever reason, he can normally end games as well.
NOTE: If you make this deck you don't need to use Red Sun's Zenith. Any bomb will work since both Axebane Guardian and Sylvan Caryatid make mana of any color. I used to run Mind Grind in this deck to go against several opponents at once. The reason I use Red Sun's Zenith is because it can target creatures, it exiles creatures that it destroys, and most importantly it gets shuffled back in when you use it which means you don't have to worry about using it on creatures.