Kiki-Jiki Mirror Breaker is a rare creature from the Kamigawa block. This deck first became popular in extended when Lorwyn came out with the card Pestermite. Here is how the combo works. Kiki-Jiki copies Pestermite. When the token of Pestermite comes into play, it untaps Kiki-Jiki. Rinse, repeat. You then have a huge number of hasty tokens with which you attack your opponent for the game.
Jump forward a few years to Rise of the Eldrazi. Wizards gave us the card Splinter Twin. Splinter Twin does the same thing as Kiki-Jiki, but isn't vulnerable to creature hate. By the time this card came out, Kiki-Jiki had rotated from Extended, so Twin took the place of Kiki in the Pestermite combo decks.
The premise is the same, but instead of the Pestermite token untapping Kiki-Jiki, the Pestermite token untaps the original Pestermite that has Splinter Twin attached to it.
One block further and we have New Phyrexia. WotC again gave us another piece of the combo, but this time playable in standard. Deceiver Exarch. Exarch is basically the same as Pestermite, but less vulnerable to red based removal spells.
About a year ago: Josh Hakakian's Twin deck at PT Philly. This is pre-Ponder and Preordain banning. http://www.youtube.com/watch?v=jh3vohtRsYU
Video: Splinter Twin in Modern
U/R Splinter Twin in Modern
xit2lni5] = WIN
Key cards for the deck that are banned in modern.
This means we have to find new filter spells. Luckily, Serum Visions and Slight of Hand exist.
Let's look at choices in the deck.
5-6 Twin spells (Kiki + Twin)
6-8 Untap Spells (Exarch, Mite)
4-6 Removal Spells
2 Flex spots depending on above choices
Kiki-Jiki, Mirror Breaker - An important combo piece. 1-2 of in the deck.
Splinter Twin - More important and arguably better than Kiki-Jiki. 4 of.
Pestermite - The other half of the combo. Vulnerable to almost all red removal, this is usually played in lower
numbers than Exarch. 2-4
Deceiver Exarch - The other half of the combo. Not as squishy as Pestermite. 4 of no question.
Serum Visions Worse than Preordain, but it's the best we have in modern right now. 4 of.
Slight of Hand Another one mana filter card. I recommend 0-4
Gitaxian Probe Free is a huge plus. Let's you check for counter before you go off. 0-4 Personal Preference
Thought Scour Instant speed draw is nice. Doesn't filter, if you're playing Snapcaster Mage it could be useful to mill yourself, but it seems just like a cute interaction.
Please tell me if I missed anything.
Spell Pierce - Good one mana counterspell. Stops everything except creatures. Usually sideboard material. 2-4 Copies somewhere in your 75
c] - Counter hate. 3-4 Copies somewhere in your 75
[c]Spell Snare - Counters Goyf, Bob, SCM, ramp spells, etc. Dispel and Pierce are almost always better in this deck. 0-2
Remand - The tempo advantage is negliable in this deck. The plus side is it will dig you one deeper into your deck. This is almost always better as a hard counter in my experience.
Mana Leak - The debate is often this vs. Rune Snag. You tend to counter things early in the game, so I would play Rune Snag 4 copies MD.
Rune Snag - See above. If you are playing 5+ mana leak style effects, play 4 Rune Snag and X copies of mana leak.
Dissipate - Counters and exiles. Solid card, but at three mana it's not really playable.
Cryptic Command - The blue Wrath of God. This card can save you in the mirror and from just losing to aggro decks. 2-
3 MD 1 SB
Spellskite Lack luster in the main, just win the counter war. Comes in from the sideboard when they bring in the hate. 2-4 SB
Lightning Bolt We're playing red, so why not play the best red card ever right? Wrong. We don't care about the "direct damage" because we're going to kill with combo.
Flame Slash The better bolt in this deck. 4 Damage at sorcery speed to a creature > 3 Damage instant speed to a creature. This card owns problem cards for us like opposing Spellskite and Linvala, Keeper of Silence
Gut Shot Killing an unflipped Delver is cute, I guess.
Dismember I tend to use Dismember as Flame Slash 5 and 6. It will likely always cost you four life, but can usually take out Goyf, Batterskull Tokens, Restoration Angel, and is a generally good answer for what
Fire Spout - Wrath is always good. If you pack at least one green source, this becomes amazing against token decks. 1-2 Main Deck.
Pyroclasm the 2 mana Fire Spout
Slag Storm Fire Spout just seems better because it doesn't tax the mana base as much.
Electrostatic Bolt Good against affinity.
These are often filled with Alternate Win Conditions.
Inferno Titan It's cute to Kiki an Inferno Titan and swing for 18. If that doesn't win you the game, then I'd be shocked.
Vendillion Clique Disruptive creature that can also help you dig deeper. If you have flex spots open, this is what I would put in.
3-5 Artifact Hate Slots
3-5 Counter Spells (pick from above, at least one cryptic command)
2-3 Wrath effects
2-4 Targeted Removal
2-4 Spellskite (meta dependent)
Cards for your SB
0-3Ancient Grudge If you're splashing green for Firespout, this is an awesome card. 3 Mana two for one against Affinity? Thanks!
0-3Shattering Spree If you're a purist and prefer straight UR, this card can often wipe an opponents field. Many people will bring in Torpor Orb to tell with you. Make sure you bring this or Grudge in every matchup.
2-3Echoing Truth Lectrys swears by this card and I also happen to think it is indeed the truth in Modern Twin (pun intended). It wrecks a tokens player's day. It takes care of pesky permanents, cough planeswalkers cough, that your flameslash can't. It is often the "bounce your torpor orb, untap, win." Against Affinity you can reset there annoying creatures or just time walk them by bouncing Memnites and Ornithopters.
1 Cryptic Command Not good enough for a full playset maindeck, but this card is indeed the saving grace
in aggro matchups and combo mirrors.
2-4 Spellskites - Depending on how many you have Main, and what your meta looks like.
Firespout in the MD just becomes larger from the SB. UR purists can play Slagstorm, even though it's worse.
If your playing Dismember in the maindeck, you'll want it out for the Aggro matchup. Swap them out for some more Flame Slash or Electrostatic Bolt against affinity.
Sample Deck list.
4 Splinter Twin
1 Kiki-Jiki Mirror Breaker
4 Deceiver Exarch
4 Serum Visions
4 Slight of Hand
2 Gitaxian Probe
3 Spell Pierce
4 Rune Snag
2 Cryptic Command
4 Flame Slash
4 Scalding Tarn
4 Sulfur Falls
4 Steam Vents
4 Cascade Bluffs
To be written by users.
Affinity (by Yanni)
Game 1 against affinity you want to go
first. Affinity has stupid explosive hands and you want to be on the defensive as much as possible until you can get off your lethal combo. Counter their mana artifacts, kill their lords, and hopefully they'll be left with a bunch of 1/1s and 0/2s. Don't be afraid to run out a Mite or an Exarch to mess with combat math for the Affinity player if you need to. As long as you can stay above 8 life or so, you should be fine.
Game 2 against affinity gets much better. You can bring in all kinds of fun hate cards. Bring in your Spellskites to eat their removal spells. Bring in your artifact hate (be it Grudge or Shattering Spree) An extra Firespout or Cryptic won't hurt either. Your matchup gets much better because you get to eat all of their creatures early and blank their removal with your skites. Often hitting with a firespout will wipe their board of everything except Master of Etherium (on the off chance they're playing it) which can then be hit by something janky. CC to sleep
their field and draw is a valid play, use it liberally. You're playing a UR control deck until you can combo.