Show Only Guru Approved Combos
Purphoros' Infinite shootBurning-Tree Emissary Buy + Purphoros, God of the Forge Buy + Cloudstone Curio Buy
Having Burning-Tree Emissary Buy +Cloudstone Curio Buy+Purphoros, God of the Forge Buy in play and then playing another Burning-Tree Emissary Buy deals infinite damage to your opponent. Also possible playing a big Genesis Wave Buy.
PermafrostKill Switch Buy + Tamiyo, the Moon Sage Buy + Mycosynth Lattice Buy
Lockdown, with the added bonus of an Emblem? Seems... Good?
Tomb of Mana FixingSpectral Shift Buy + Urborg, Tomb of Yawgmoth Buy
Self explanatory. Especially useful in EDH due to the color identity rule.
Since Urborg is considered colorless for the purpose of the color identity, any variant blue deck you run can be helped out immensely using this trick.
Stack AttackMist of Stagnation Buy + Temporal Cascade Buy
Play Mist of Stagnation, then follow up with Temporal Cascade, choosing to shuffle in all graveyards and hands into libraries.
Feel free to use cards like Jeskai Ascendancy Buy, or Seedborn Muse Buy, in order to help get around the Mist of Stagnation drawback.
Or, you can just be mean and use Eon Hub Buy. =P
Mill 3 cards for 1 mana, minimumSphinx's Tutelage Buy + Prosperity Buy
Prosperity makes them mill 2 because you draw, plus they have to draw also which makes 3 cards for one mana. Gets worse if they have same color, no lands in those 2 cards.
Clear As MudUgin, the Spirit Dragon Buy + Painter's Servant Buy
-0: Exile all lands.
Not really a drawback if you run mana rocks.
Hitting a Swarm NestPalisade Giant Buy + Darksteel Plate Buy + Druid's Call Buy
Please do not rate for originality - I searched and found that these things were not together, but the pieces were already posted.
I like this slightly better than the one in the link because in addition to the damage prevention, you get a swarm of un-damageable tokens:
Damage Shield by Captain Nemo
Nature's Abundant AggressionBear Umbra Buy + Waves of Aggression Buy + Abundance Buy
Bear Umbra can be subbed for Nature's Will Buy, or Sword of Feast and Famine Buy.
This combo also needs a way to draw a card as a result of attacking, such as Overwhelming Instinct Buy.
Net Result, when successful:
X Combat Phases, where X is the number of lands in your deck.
This 4 card interaction is a variant on the Aggravated Assault (or Hellkite Charger) + SoFAF interaction.
To make this infinite, Reito Lantern Buy is required as well.
Enlightened IdiocyNarset, Enlightened Master Buy + Proteus Staff Buy + Fervor Buy
Play all three, and enough mana to activate staff. Any Haste mechanic will work here.
Then before swinging with Narset, activate staff targeting Narset.
3, T, Attack: Go find 4 non creature spells and play them for free. Then, stack your deck if you so choose.
EDIT: Credit to Hexyl for pointing out Staff was only at Sorcery speed.
Temporal ManipulationNecrotic Ooze Buy + Phyrexian Devourer Buy + Sage of Hours Buy
Just like any previous Ooze combo, get the others into the yard any way you can.
Turn your library into a number of extra turns equal to the total number of counters added on, and removed, this way, divided by five.
Interestingly enough, if you substitute Sage of Hours for Workhorse Buy, you get colorless mana instead.
Lab Maniac, FTW?! =P