My history with this deck is that Doran, the Siege Tower was the second true deck that I built back in early 2011. My first deck was an Esper midrange control deck, and what I loved about the Necra wedge (now known as Abzan) was the versatility it offered: removal and decent creatures in all colors, mana fixing in green, and general tutors and card draw in black. I built Doran as a faster aggro deck, designed to ramp Doran out on turn two, and by turn three get him swinging with equipment. So when the first precons came out I was excited to get new cards for this wedge. Little did I realize, Doran would quickly shift into Karador, and the deck has been a part of my collection ever since. The reason I like it is that I enjoy being a control player, but this is a more interactive form of control, rather than solely interacting on the stack. It also is a toolbox deck, so it never plays the same and different board states call for different cards.
Pitfalls to Avoid
I want to start with this section first because I feel that it is applicable to most Karador decks, as well as recursion decks in general. There are certain things that you want to avoid doing when playing a graveyard based recursion deck, because these decks tend to play slower and you don't want to tip off your opponents or draw attention to yourself.
2. In the same vein, don't rush to become the threat. In the midgame you can certainly become capable of locking down a battlefield and keeping problem permanents off the board, but not in the early game. So don't get in a hurry to play cards until you're ready to use them. Along these lines, if you have removal, use it on the scary cards. Your opponents might not be as worried that you can do some scary things if you're helping them save their removal.
Opening Hand and Early Game
The ideal opening hand gets you to three to four mana of all colors, with at least one mana dork, one utility creature of midcmc, and a value artifact or enchantment. Hands with Birthing Pod or Gift of Immortality along with a cheap sac outlet are almost always ones you keep so long as you have the mana and a creature to support them.
The goal of the early game is to get a solid mana base and start durdling with inoffensive utility creatures. If you can set this up then you will be well positioned later to start doing multiple things in one turn.
The Mid Game
If your early game went smoothly, then you have been hitting every land drop and ramped a little. You shouldn't have had any problems getting to six mana and have a sac outlet. At this point your main focus is going to be keeping other players boards under control (within reason, don't overextend and don't dip into stax territory so as to not make yourself a threat), and to not empty your hand. This stage is when other players will start to do threatening things - you should carefully use your removal to slow them down, which probably also helps stock your graveyard. This is good! A reanimator player with a full graveyard is scary, so if you can bait out other people's Tormod's Crypts and Nihil Spellbombs now then you will be in good shape later on. As I stressed earlier, you shouldn't throw things into your graveyard if you can avoid it, so if you haven't yet set up an engine for winning the game you should be baiting removal rather than playing around it. Also, you'll want to keep hitting land drops and ramping. You'll need all that mana soon.
The goal of the mid game is to slow down your opponents, continue ramping, set up an end game engine, and baiting out graveyard removal.
The End Game
There are a few different ways to close out the game. The easiest is to loop Karmic Guide and Reveillark along with a sac outlet and finisher (such as Blood Artist or Gray Merchant of Asphodel). You can also use a loop with Ashen Rider to exile a board, or use Vish Kal, Blood Arbiter and a loopable creature to keep all other creatures off the board and swing with combat damage. The way you attempt to win will all depend on what creatures you still have access to. The nice thing is about some loops like Gary or Kokusho are that you don't need to go infinite with them, just a couple of loops is sufficient.
The goal of the end game is to win (duh) through one of the deck's combos.
There are a few cards that work very well in this deck that I have consciously chosen not to add:
Protean Hulk - This is basically a one card win condition. Sac it once, grab Karmic Guide and Viscera Seer (plus Dryad Arbor if you run it). Karmic Guide brings Hulk back to play. Sac it again, this time grabbing Reveillark and another one drop if you wish. Sac Guide again, then sac Llark, bringing back the Guide, which brings back Hulk. Sac Hulk again for Blood Artist or Gary. Rinse and repeat ad nauseam. The reason I don't run Hulk is because even though this is a combo deck at heart, it is one that gets there by naturally assembling its own pieces (which is also why there are largely no tutors in general). Ironically, when Hulk was banned I really wanted it unbanned so I could abuse use Hulk. What I found as soon as I added it to the deck was that it was predictably as good as expected and that there really wasn't a correct answer when you had it other than to just assemble the combo and win, and I didn't want this deck to do that.
Triskelion - You'd think that since I'm already running Mikaeus, the Unhallowed that I would run the other half of the combo. But on its own Trike is just a bad card. The goal isn't to avoid infinite combos, it's to just let them happen naturally with cards that are good on their own merits.