Pre-Paradox ban Sisay (EDH / Commander)

Combo? Stax? Why not both?

Meet Captain Sisay, my toolbox commander. She's a catch-all to dealing with other combo decks. When playing Sisay (and especially, when building Sisay) know what type of decks you will be going up against, so you can tune her appropriately.

Step one of this deck is to get Sisay out. Use mana ramp like Elvish Mystic and Avacyn's Pilgrim to get her out quick, and (when possible) use Concordant Crossroads, Hall of the Bandit Lord, Thousand-Year Elixir, or Lightning Greaves to give her haste. Then you need to figure out your next course of action...

SETUP
If you're getting worried about one or more of your opponent's, go for the stax route. Otherwise, build up your board a little. Selvala, Explorer Returned, Rishkar, Peema Renegade, and Dosan the Falling Leaf will help with ramp and protection. Once you're comfortable, grab Paradox Engine. This will make things very easy for the future, but be warned; as soon as you play Paradox Engine, there will be a massive target on your back. This is why you grab Dosan. Generally, you want to grab Paradox Engine only if you have one or more mana-providing permanents that can be untapped (so lands don't count). If you have three or more: great, you're ready to combo. Otherwise, use Sisay to get Mox Amber and Mox Opal for your second and third mana source, after getting Paradox Engine first.

STAX
If you did the SETUP step, you could very well play all of your stax pieces in one turn. However, you'll often go the Stax route if someone else is more likely to combo first. Some of your go-to cards should be Linvala, Keeper of Silence, Hokori, Dust Drinker, and Elesh Norn, Grand Cenobite. If you also have Nature's Revolt, then you have successfully soft-locked your opponents (Elesh Norn destroys all of their lands, Linvala stops them from being tapped for mana). You can also use Gaddock Teeg and Brisela, Voice of Nightmares to limit your opponent's to only casting creatures. If the opportunity present's itself, use Armageddon. Sisay can also search for legendary lands, so you will recover faster than everyone else. Take note: Gaddock Teeg stops this deck's combo (you can't play Paradox Engine), so you'll need to get Miren, the Moaning Well to get rid of him.

COMBO
For these combos, you will need Paradox Engine. If someone uses Krosan Grip on it, may they feel the wrath of your stax effects (or use Bow of Nylea to get it back). You will also want artifacts and creatures that tap for a total of 3 mana (at least). If ever you need more mana, you can always tutor for legendaries like Mox Opal, Mox Amber, and Seton, Krosan Protector, which will give you more untaps.

The first method is with Selvala, Explorer Returned. Tap her to draw, cast something to untap, do it again. Thousand-Year Elixir will help to give an extra untap, so you'll (almost) always have something to cast (Use Inventors' Fair to get Thousand-Year Elixir). Keep casting Green-Sun's Zenith, so you don't deck yourself... only your opponents. This method is risky (especially without Dosan), and annoying, so I don't recommend it.

The second combo uses Bontu's Monument (you're allowed to use it, it has no color identity). You'll need 3 mana-providing nonland permanents. After Bontu's Monument, get Bow of Nylea, and then Mikaeus, the Lunarch. Now you're ready for the loop. Cast Mikaeus for 1 mana, and have him die as a 0/0 (Bontu's Monument does 1), Use bow of Nylea to put him back into your library, and then use Captain Sisay to grab him. Recast Mikaeus, everything untaps, and Bontu's Monument drains all your opponents. Repeat until you win.

Retired Combos:

This method involves Blasting Station. You'll need 3 mana-providing nonland permanents. Use Sisay to get Inventors' Fair, and then use Inventors' Fair to get Blasting Station (If you need three artifacts, Mox Amber, Mox Opal, Hope of Ghirapur, Paradox Engine, and Bow of Nylea can all be searched for). If you already played a land that turn, Azusa, Lost but Seeking will give you another land drop. Next, use Sisay to get Bow of Nylea, and then Hope of Ghirapur. Now you're ready for the loop. Sacrifice Hope of Ghirapur to Blasting Station (deal one damage), Use bow of Nylea to put it back into your library, and then use Captain Sisay to grab it. Recast Hope of Ghirapur, everything untaps, and then repeat until you win. This combo was removed because the same thing works with Bontu's Monument, but you skip the "search for Inventors' Fair step"

A final combo involves looping Saffi Eriksdotter, with Bontu's Monument and Bow of Nylea. For the loop, sacrifice Saffi, and use Bow of Nylea to put her back into your library. Use Sisay to put her in your hand, and then recast her (untapping everything) to deal 1 damage with Bontu's Monument. This loop takes 4 mana each cycle (2 green, 1 white, 1 generic), so make sure you have enough mana providing nonland permanents. Bloom Tender and Rishkar, Peema Renegade will do the trick.
NOTE: I took this combo out because it has too many pieces that only work for this combo.