The primary goal of this deck is victory via creature stomp. So obviously, there are plenty of large scale, powerful creatures from each of the five colors to dominate the field like Maelstrom Wanderer, Terastodon, Elesh Norn, the Angels, the Bringers and the victory god, Iroas. Thus getting them on board and keeping them there is obviously the primary goal, but not the only way to victory.
The best place to start is obviously the mana. As a five color deck, the mana base will need to be as flexible as possible without sacrificing too much in terms of speed. There's the typical staples like Command Tower and It's ilk, but for real color diversity, there's Chromatic Lantern. Like it's fellows, Darksteel Ingot and Gilded Lotus, It can provide immediate benefits by tapping for mana the moment you cast it. But the lantern extends it's own effect to all other lands in play, expanding what you available mana base can do dramatically. Toss in a few search lands and you've got a strong showing to support the mayhem that'll swiftly follow.
Early game has a long lineup to establish an initial mana base and swift board presence. Birds of Paradise and Noble Hierarch supplement the mana base and Weathered Wayfarer acts as a great equalizer/deck thinner while Glen Elendra and Grand Abolisher keep the enemy at bay and the cards on the field.
Once a foundation is established, the big guns are whipped out with all haste while at the same time, work begins on making those behemoths more and more difficult to get rid of. Elspeth fills both rolls well by providing chump blockers or offensive buffs while building up to her emblem. Many of the creatures themselves have global effects that extend to the entire line up but if all else fails, Avacyn or Privilaged Position can establish instant protection field wide.
Perhaps one of this decks more creative fuctions is playing off the top of the deck since it essentially functions as an additional card in hand. There in lies the power of Future Sight. Oracle of Mul Daya, meanwhile is two-pronged, accelerating your mana drops and taking that mana off the top of your deck, clearing the way for something more vital beneath it. It's for this purpose that Sensei's Divining Top is here. It's utility in constantly manipulating that top card works perfectly in concert with the rest. So when played right, top decking will accelerate you through your deck and allow for more aggressive fighting.
As for the creatures, since a lot of them are expensive summons, there's a myriad of ways to cheat them onto the field. Quicksilver Amulet and Elvish Piper are self-explanatory while Lurking Predators taps into both the goal of summoning monsters and playing off the top, again manipulating the deck to your advantage. And for those poor souls that got taken out early, Sheoldred and Debtors' Knell will bring them back to stomp anew.
Finally, we have end game, for when worst comes to worst and someone needs to die now.
The first and most obvious win condition is Progenitus itself. The instant it hits the field, it'll immediately raise a red flag in the minds of all the other players and any amount of collateral suddenly becomes acceptable if it means getting him off the field. So aside from preventing board wipes, the best course of action is to minimize the number of attacks needed to hit the target 21 commander damage. To that end, there are myriad ways to provide Progenitus with additional powers that function despite his own universal protection.
Opal Palace, as a start, can be used to apply one or more +1/+1 counters to Progenitus before he hits the field. So even in the first use, Progenitus now needs only two attacks to hit the twenty-one damage target rather then three. Archangel of Thune and Elesh Norn can continue this trend of adding power to him since each of their powers are global, affecting one or both sides of the field indescriminately, one of the only functions in the game that gets around Progenitus' defenses. In the same vein, Many creatures and planeswalker emblems can all grant Progenitus additional keyword powers which upgrade his threat level further still. The most important among these are Haste, Indestructible and Double-Strike which, if used in tandem, may not even give an opponent one last turn to form an answer to your commander.
Of course, relying on a single creature every time is a recipe for distaster no matter the strength. But every planeswalker worth his salt always has a back-up plan. And I have three.
Primal Surge takes the ultimate goal of this deck and runs with it, summoning huge volumes at a time and possibly some new mana to summon more with. it's for this reason the deck carries only a couple Instants and Sorceries. With so few, they can easily be accounted for before casting the Surge, ensuring there's little that can stop it before a decent summoning spree has happened. Lets see your opponent overcome your brand new front lines.
The next is to play off the indestructibility inherit to several of these cards and embracing the field wipe effect. Obliterate had been swapped out in favor of Supreme Verdict. This is usually only used when faced with a tremendous threat that you don't have an immediate answer to. It's best used if some or all of your cards on the field are indestructible which will ensure they survive the blast and be available to act against a suddenly vulnerable opponent. And since it only targets creatures, all the mana and utility cards on your field will go untouched which will be a tremendous aid in recovering from the field wipe. The best time to use this spell is by first activating Elspeth's emblem or summoning Avacyn. If either one hits the field, then Supreme Virdict is no longer a last resort. It's an option.
Finally, the last and quite likely the most effective win-con Is a combination of two creatures; Aurelia, the Warleader and Medomai the ageless. Medomai's power to grant an additional turn on a successful hit is huge even if he can't attack during those turns. But what if he can land more then on hit before your initial turn ends? With help from Aurelia, he can. There is nothing stopping Medomai from swinging for a second hit during the second combat phase Aurelia provides. And since Medomai grants an extra turn for each successful hit, that means you'll be taking two extra turns after the first. And with Aurelia providing a second combat round for each turn, that equates to six combat rounds in a row. That should provide more then enough time to bash in the faces of all your opponents. Just be prepared to apologize as thoroughly as possible. Such a tactic runs the risk of your playgroup banning this deck from all future play.