Infinite Damage!  With all three cards in play and Deathrender attached to the Fanatic, sacrifice the Fanatic to deal one damage to an opponent (or creature).  Because Enduring Renewal is a replacement effect, it affects the Mogg Fanatic during the resolution of the trigger from Deathrender. And thus, you can take that same Fanatic from your hand (that just got there thanks to Renewal) and put it into play with Deathrender attached to it. 

Replace Mogg Fanatic with other creatures that sacrifice for free with an effect for other types of infinity.

Infinite Damage! Without the Grapeshot, this is in infinite loop combo capable of super-high storm counts.  With the Grapeshot your can deal infinite damage.  How does it work?

With both the Basal Sliver, Skeletal Changeling and Haakon in play, know that the Skeletal Changeling is all creatures types so it is a Sliver and a Knight.  You can sacrifice the Changeling for BB.  Then you can use Haakon's ability to replay it from your graveyard with that two mana.  Repeat this as many times as you like and then follow up with a Grapeshot for infinite damage.

INFINITE DAMAGE!  Note this was partially submitted by Aneximines.  Tidewater Minion can tap to untap himself (itself really) as many times as you like.  Ceaseless Searblades get +1/+0 every time an activated ability of an elemental is played.  And thus, the two cards interact to net your Searblades infinite power.  Add Fling to the mix and suddenly you can deal infinite damage to a target.  Sounds like fun to me. 

Note that if Tidewater Minion isn't your cup of tea you could always add Unnatural Selection and substitute the Minion for Seeker of Skybreak or Aphetto Alchemist.  As long as the creature can keep tapping itself to untap itself, you are good to fuel the Searblades.  Obviously, you'll want to make it an elemental with Selection...

Until Wizards of the Coast gave the Drake errata, which reads "if you played it from your hand...", this combo was an excellent way to make your opponent cringe.  The way it worked was that you enchanted the Drake with Demise and then sacked it to the Goblin Bombardment.  Because of the ability on Demise, the Drake came back into play, and because the ability on the Drake so did the Demise.  You could repeat this combo until you were blue in the face, or until you opponent died from Bombardment damage.  Too bad the combo no longer works.  

UPDATE: 7/15/07 - The previously added errata was removed.  The combo works again!

This is a tricky combo that started off as just a Jedit - Yavimaya card interaction submitted by Niv-Mizzet_Rulez!  Then uber_panda suggested adding Breath of Fury for infinite damage.  Then YWN quickly advised you needed to give the tokens haste for the combo to work.  Phew.

In the end, here's what happens: Have Jedit, a 2/2 green Cat Warrior token and Mass Hysteria in play. Note: Yavimaya is the card that enables all of your cats to be unblockable since she gives your opponent a forest.  Otherwise, she doesn't matter to the sequence of this combo.  The token needs to be enchanted with Breath of Fury.  Attack with Jedit and token.  Jedit generates another token.  Jedit and the original token are unblockable and thus they deal damage.  Sacrifice Breath of Fury and attach it to the new token.  Untap Jedit.  Now attack with the new token, which has haste thanks to Mass Hysteria and Jedit.  Repeat to inflict potentially infinite damage.

Wizard's said themselves they were worried about Timeshifting Enduring Renewal for the same reason Enduring Renewal was dangerous back in the day: infinite combos.  This time around those pieces are different: Grapeshot and Wild Cantor.  For those who didn't know, the old pieces were Goblin Bombardment and 0cc artifacts (like Phyrexian Walker).

How it works: With Enduring Ideal in play, Wild Cantor in play and Grapeshot in hand, Sacrifice Wild Cantor to add a red or green mana to your mana pool.  Enduring Renewal will return Wild Cantor to your hand.  Use the mana you generator from the Cantor previously to cast it again.  Repeat this infinite times.  Then cast Grapeshot to infinite damage. [Enduring Plans]

I had to post this in fear of getting 3000 emails about the same combo.  Many people have already submitted it via email and in the forum.  OK.  This is simple.  Enchant Niv-Mizzet with Curiosity.  Now, tap Niv-Mizzet to draw a card.   Niv-Mizzet deals 1 damage to target creature or player (preferably an opponent). Curiosity activates again, drawing you a card and thus dealing another point of damage - dealing up to infinite damage to an opponent.  Well, infinite in terms of as many cards are in your library infinite.  Thanks to everyone that submitted it.

Also note that there are many cards that work well with Niv-Mizzet.  Some cards that come quickly to mind include Invoke the Firemind, Greater Good and Mindmoil.  Have fun!  (Necrologia is also an interesting idea thanks to retarded_a_i in the forums.)

Note: Memory Crystals will turn this into an infinite mana combo.

This infinite combo was submitted by Matt J. (which replaced the combo referenced below in yellow.  To quote his description: "Play Pandemonium. Play Sekki. Sekki deals 8 damage to itself. Sekki removes the counters, putting 8 1/1 Spirits into play. Each of these Spirits deals 1 damage to your opponent. Sacrifice these Spirits, returning Sekki to play. Sekki deals 8 damage to itself..."

Note: The original combo with Blasting Station and Sekki do not work.  EinsteinMonkey and I forgot about the 'sacrifice a creature' part of the activation cost to tap the blasting station.  Thanks to anonymous and another guy from Germany for pointing this out in an email to me.

With Pandemonium and Aluren in play, cast your Horned Kavu for free.  Assuming you have another Horned Kavu in play, send the first Kavu back to your hand and then cast him.  Each one sends the other back to your hand for you to cast again for free with Aluren.  All the while, your Pandemonium activates and deals damage to your opponent's side of the board.  Nice. 

Also, know there are cheaper alternatives to Pandemonium: Brain Freeze and Furious Assault. Also, there are many alternatives to Horned Kavu: Man-o'-War, Cavern Harpy, Fleetfoot Panther, Lava Zombie, Shrieking Drake, and Silver Drake.  Thanks to Anemimines for adding some additional information to this concept. 

They made the Scythe +2/+2 to prevent this.  You can still do it with the Carrion Feeder, though (or any other card that sacs a creature).  Enchant the Triskelion with the Scythe and deal one point of damage to the Skelion and 2 points to your opponent.  Sacrifice the Skelion to the Carrion Feeder and then it comes back into play with a fresh set of three +1/+1 counters to use.  Repeat until you win.  Not bad.  Thanks, Michael, for the combo!

Ok.  So Mind Over matter is banned.. who cares.  This is still a fun combo that works with a variety of cards like Kamahl, Timmy, Thornwind Faeries, and so on.   Enchant your pinging creature with the Curiosity and tap it to deal damage.  Draw a card through curiosity and then discard a card to untap it.  Deal damage until your blue in the face or until you run out of cards or until your opponent(s) are dead.  Throw a Thran Foundry into the mix and you are sure to win any group game.. assuming you opponent(s) cannot target your Pit Fighter or Wizard or Faerie to destroy it.  Fun. 

Note: the deck to the left uses the concept of this combo.  This combo was submitted by Steve V.