Once you’ve played a decent bit of MTG combos seem to form patterns. Your eyes are not fooling you: all combos file into at least one of the categories below.
A+B combos are where you have one card that enables another card to create some type of renewable value that creates a cycle, and does not require mana input for every cycle.. Kiki-Jiki, Mirror Breaker targeting Deceiver Exarch will make a copy of Deceiver Exarch that you can use to untap Kiki. Mikaeus, the Unhallowed enables Triskelion because when Triskelion dies without a +1/+1 counter on it it comes back into play. This allows you to deal an infinite amount of damage as long as you are allowed to maintain your loop.
This is the greatest strength and weakness of A+B combos – you are building an incredibly powerful loop but you often need a channel to deploy the value you are establishing with your loop. With the Kiki/Deceiver combo you need your attack step to end the game so you can attack with your infinite Deceivers.
Both Kiki combos and Mikaeus, the Unhallowed are vulnerable to spot removal but the decks that deploy these types of strategies have features in their deck design that allow them to possibly reengage their combos or wait for opportune moments to start their combo. With Kiki/Deceiver Deceiver Exarch has flash so you can flash in Deceiver after your opponent taps out and threaten to win the game. Mikaeus is in black so you can reanimate Mikaeus if he dies to traditional spot removal spells and reengage your combo.
(A+B) + C Combos
These combos are very similar to A+B where you have one card enabling another but you need a third card to assist with delivering the output you require to win the game. The most classic examples of this type of combo family involve sac outlets. Cards like Altar of Dementia can mill everyone out if you can create a loop that gives you a creature every time you sac a creature. These third cards can also include mana sinks like Staff of Domination or other cards that allow you to generate value after you establish a A+B combo that generates unlimited mana.
These combos are pretty rare. They usually involve having several of one type of permanent in play (like Biovisionary ). The newest card to join the ranks of this rare family of combos is Mechanized Production.
These types of combos end up looking like A+B or (A+B) + C combos but they start with a much more detailed sequence. People who play with Karador in EDH know that Boonweaver Giant can get Pattern of Rebirth. If you have a sac outlet you can sac Boonweaver, triggering Pattern to find Karmic Guide (reanimating Boonweaver, which can get Pattern out of the graveyard). You sac Boonweaver again to get another trigger off of Pattern – this time finding Reveillark. This will lead into a loop where you can get Reveillark to revive Karmic Guide (which lets us revive Boonweaver) and start netting creatures and win the game via any number creature combos.
With Protean Hulk when it dies you can do a similar function – find a number of creature combinations that eventually sculpt into A+B or (A+B) + C combos. While Protean Hulk is banned in EDH people usually use the card Flash to initiate it’s combo sequences.
Momentum combo decks are just as they sound – they require momentum (either over several turns or a burst in a single turn) that can be transitioned into a lethal boardstate.
I built a Breya Eggs deck where you can cantrip cheap artifacts such as Pyrite Spellbomb or Sunbeam Spellbomb (there are many other 1 CMC artifacts that cantrip in a similar manner) to eventually cantrip into mass artifact reanimation spells like Scrap Mastery, Open the Vaults, or Roar of Reclamation. This type of deck is momentum based because you need to fill up a certain zone with value before the rest of your deck can capitalize. With the Breya Eggs deck you can often cantrip, cantrip into more cantrips, and eventually mass resurrect your artifacts to cantrip several times and string multiple mass artifact reanimation spells in a single turn. This lets you find other combos that exist in the deck during this mass cantrip turn and win the game.
Storm decks are probably the most popular form of Momentum combo decks – they care directly how many spells you’ve cast on the turn that you combo off and usually require super high amounts of card draw or mana production (often facilitated via Ad Nauseam) in order to carry out their combos. They also use cards like Past in Flames or Yawgmoth’s Will to give them the virtual card advantage they need in order to develop a high enough storm count to win the game via Tendrils of Agony.
When Death’s Shadow decks were more aggressive in Modern they would be an idea example of what a combat combo deck is – a deck that uses aggressive creatures with a few combat tricks thrown in that threaten lethal burst damage.
Infect decks are probably a better example – the infect mechanic synergizes with pump spells because we only need 10 infect to kill an opponent.
Back when Atarka Red was in standard players would utilize cards like Krenko’s Command and other small mono red style creatures to push in early damage and threaten to win the game out of knowhere with cards such as Temur Battle Rage and Become Immense.
Conditional Combos rely on the gamestate being a certain way before the combos can be lethal.
With Channel and Fireball, as long as your life total is at least 1 point higher than your opponents you can win the game by taking yourself down to 1 to generate a ton of mana and Fireball your opponent.
Scapeshift deck are somewhat conditional because players are somewhat limited in deck design as to how many mountains they can run in their deck. Sometimes they also need a high enough land count in play before casting Scapeshift so that Valakut, the Molten Pinnacle actually kills their opponent.
All conditions that care about your lifetotal also fall into this category; Felidar Sovereign, Test of Endurance, and a few other cards such as Near-Death Experience allow for you to win the game when you reach certain very high or very very low life totals.
What are some of your favorite combos?