Before explaining the combos I´ll explain our main pieces briefly and some notes:

• Adding dual color green and blue digimons gives us the strong Imperialdramon shenanigans, as well as giving us Davis as a consistency tool. Memory boosts aren´t great here since we can work as a fast aggro deck, but Davis being an always functional searcher + possible double search is huge. Also it unlocks Ice wall as choice. Davis & Ken is the best card here since we can unsuspend all our digimon when we digivolve them.
• Lighdramon is the best non-alliance LV4 of the deck. Since it´s 2 color green digimon, our LV5s can evolve for 3 (or 1) on him. He also gives us 2 memory from each Davis & Ken after promoting, and its when digivolving effect can be really useful on cleaning cheap threats. It also provides a blue source to unsuspend Imperialdramons to continue attacking.
• Keep in mind that the archetype deck is “dual color green digimons” not just the rabbit ones, so we can abuse cards that don´t have Alliance. This means we can add Imperialdramons and Lighdramon with our searching rookies.
• All the EX4 rookies share the inherited effect “When you suspend a digimon with Alliance, this digimon can digivolve for 2 less into a dual color green digimon”. The whole deck will try to abuse this mechanic. It´s important to remember this is NOT once per turn, and this can be activated although the suspended digimon is not attacking. So we can even have this effect on a digimon A, attack with B, activate Alliance suspending A, and digivolve A for 2 less into a new digimon.
• The deck contains ways to recover cards from trash, recover cards at security, playing cards from trash and even run Quartzmon, Ice wall, do OTKs and clean boards from different angles. It´s good at playing midrangy games. There are tons of good dual green digimons and some options can still be explorer, as well as builds with Hidden Potential Discovered to extend plays.
• Which Imperialdramons are the best? I consider playing 3-4 copies of BT12 Imperialdramon Dragon Mode (DM from this point to abreviate) is necessary. About Fighter Modes, they serve for different purposes. FMBT8 is good at fast metas, removing threats and staying aggro. FMBT12 is stronger in long games since it can recover you a DM from sources, attack for more checks and block. Both are good options so I will leave the choice of which one is better to you, as you can adapt them to fit your necessities.
• Dual tamer Henry & Su-Chong. Is is worth to play? Yes, in some scenarios you would want to play in a conservative way, or just stablish setup while memory choking to win some time while gathering your pieces. This way you could deploy a complete combo line with just your breeding + the rookie you play with this tamer´s effect. I can see myself playing this tamer with memory boosts or more searching tools.

Now that we know all this points, let´s explain the main combo line. After this, the rest of combo lines will depend of what resources do we have and what can we do with them. I´ll explain the outcome of each line so we can identify which one is the best we can do with the cards we have:

Combo Line 0: The Standard combo

We need any Digimon in play and a LV5 rabbit with an  EX4 rookie at its sources. Promote the LV5, attack, activate Alliance, suspend the other Digimon to get Sec+1 and DP boost, draw 1 because of the digi-egg, trigger inherited from rookie to digivolve for 2 into DM. DM´s when digivolving effect will always suspend a Digimon, for example an opponent´s blocker, and could unsuspend the DM. The attack of 12k+DP  and 2 checks resolves, then the End of attack effects activate, DM´s effect digivolves itself for free into a FM, and then FM when digivolving can bounce a digimon. If FM is BT8´s one, a 10k or less. If FM is from BT12, we can add DM back to hand and return the digimon we suspended before to bottom of the deck (and all digimons without sources with it).

This way our final board is:

• A FM.
• A suspended Digimon.
• 1 card drawn because of the digi-egg. (+1 card economy)
• 2 cards cycled in our hand since we digivolved twice during the combo. (+0 card economy)
• An opponent´s digimon bounced to hand or deck (+1 card economy, +X if bottom decked multiple ones with FMBt12)
• And a potential DM in hand with FMBT12 (+1 card economy)

The total card economy won is +2 with FMBT8 and +3 as minimum with FMBT12, with a lot of comeback potential in our hand. Once we understand the value of the main combo line, the rest of the combos are basically situations where we have less resources to work with, concrete pieces or extensions of the same combo which depend on additional cards on our side.

Combo line 1: Standard combo but we only have DM

If we don´t have FMs in hand, we can still do the standard combo to hit with 12k or more of 2 checks while suspending an opponent´s digimon. We can evade a blocker Digimon or avoid a redirection since DM will be pretty big and our opponent won´t probably redirect this attack since his digimon is dead most times if he redirects. We can extend this play by Digivolving then into Quartzmon and close the game next turn. If we have Davis & Ken we can unsuspend it anyways to attack the digimon we suspended and remove that threat.

Combo line 2: Standard combo but we only have FM

At this scenario we can still digivolve for 3 cost into FM. Depending on which FM we play, we can bounce something when digivolving. Obviously FMBT8 is superior in this scenario since it doesn´t rely on having DM as a source. Anyways, FMBT12 here is attacking for 3 checks with more than 13k at one single attack, so it´s not a bad play on his own. If we can unsuspend it with Davis & Ken we can attack again for 2 extra checks cleaning the whole security stack, or if we passed turn while evolving, we can unsuspend it to have a strong blocker.

Combo line 3: The level 4 is Lighdramon

Having Lighdramon means that DM will always unsuspend itself when digivolving, so we can extend our combo with extra attacks. So this basically means that the combo variates: 

Promote the LV5, attack, activate Alliance, suspend the other Digimon to get Sec+1 and DP boost, draw 1 because of the digi-egg, trigger inherited from rookie to digivolve for 2 into DM. DM´s when digivolving effect will always suspend a Digimon AND unsuspend the DM. The attack of 12k+DP  and 2 checks resolves, then the End of attack effects activate, DM´s effect digivolves itself for free into an unsuspended FM, and then FM when digivolving effect cleans board. If we are in our turn (starting with at least 2 memory warranties it) we can then attack, unsuspend and attack again with FMBT8 or attack for 2 checks with FMBT12. Both FMs do the same damage here. But we did a total of 3 attacks, potentially winning on that turn. 

Combo line 4: The level 4 is BlackGargomon

Nothing to remark here, the combo is basically the same but with an extra 2k boost. It´s not that worthy unless we want to hit over something like a BlackWarGreymon X or something really big that we want to suspend and then attack again. I´m not running the card since the deck has other ways to deal with this type of threats.

Combo line 5: The level 4 is Turuiemon

The EoA effect of Turuie lets us do -2k DP reduction at an opponent´s digimon, cleaning rookies. The real combo comes with FMBT8 since we can just do -2k with first EoA, then DM´s EoA digivolving into FMBT8 bouncing a digimon with 12k or less. This combo lets you bounce LV6s with FMBT8, or reduce the DP of the Digimon you suspended with DM to attack it later and assure it dies. 

Combo line 6: The level 4 is Wendigomon

This is when this becomes Yugioh. Wendigo´s EoA lets you return a green digimon from trash to hand. This can lead you to several extensions of your combos. One example could be returning a FM from trash with the first EoA effect, then use DM´s EoA to evolve into the FM you just recovered. You could also return a Quartzmon to digivolve into your LV6. You could get a rookie or a missing piece for the next turn. You could recover BT3 Terriermon to close turn with a memory blocker… Wendigo opens too many doors. 

Combo line 7: Davis & Ken is in the board

Basically Davis & Ken lets you unsuspend whatever you evolve into. This is like having Lighdra at sources, assuring your DM from standard combo unsuspends. That´s the most obvious utility of this tamer, but we need to consider that the effect of our EX4 rookies is not once per turn, and it does not require that we activate the effect on the digimon who is attacking. 

So one interesting and powerful play is: Promote Lighdra, get +2 memory.

Digivolve the other Digimon into any Alliance body, attack and suspend Lighdra for 2 checks with dp boost. Trigger digi-egg to draw 1, then Lighdra´s inherited to digivolve for 1 into a LV5. Activate Davis & Ken to unsuspend your new LV5. Then the 2 checks are done, and you can still attack with your LV5 (and go for an additional 2 checks with alliance if we have another digi to suspend). 

So basically having one or more of Davis & Ken does not only give us memory to play, it generates lots of situations were we can basically OTK our opponents and keep attacking until we are bored.

Davis & Ken also open the following combo lines, allowing us to deploy an extended version of the standard combo, but this time we can promote from LV4, and do more powerful plays. having multiple copies of Davis & Ken is also letting us to do really big shenanigans with the extra memory and the additional unsuspends we got.

Combo line 8: Davis & Ken + Alliance LV4 + The level 5 is BlackRapidmon

The combos with Davis & Ken lets us use twice our EX4 rookies inherited effect. First time evolving from LV4 to LV5, and a second time from LV5 to LV6. The point here is that we can resolve the LV5´s EoA and also unsuspend it with Davis and Ken for a new attack. If the LV5 is BlackRapidmon, we have the weakest version of the combo, having 2 attacks. The first one with 2 checks and De-Digivolve 1 at an opponent´s digimon, and a second attack for 1 check. With an additional digimon to use Alliance, we can also digivolve into the Imperials and do the classic stuff, specially at FMBT8 to bounce it since it will surely be a LV5. this is useful against BWGX or Machinedramon, since we an warranty that de-digivolve effect. The single attack of Rapidmon is also OK as we can get a second de-digivolve if we are interested on it, and then we can just hard evolve into FMBT8 to bounce that body.

Combo line 9: Davis & Ken + Alliance LV4 + The level 5 is Yellow Antylamon

Yellow Antylamon´s EoA allows us to recover 1 security when our securities are 3 or less. We don´t need to explain why this effect is so powerful. We can heal ourselves once with the first attack and then proceed to the standard combo, or just heal twice and then evo into a FM to bounce/block in case of FMBT12. I´m also running 3 copies of Lightning Judgment from EX4 with is insane in this deck, since it does X+1 times -6000 DP, where X is the amount of colors we control in our Digimon. I don´t like removal options unless we have recovery in the deck, but we do, so it´s not weird to do recoveries into options in the security as we take the digimons out of our deck with searchers, making the probabilities of recovery into an option bigger.

Combo line 10: Davis & Ken + Alliance LV4 + The level 5 is Purple Antylamon

As it happened with Wendigo, purple Antylamon opens the door to the biggest combos. This time it has an EoA that revives a LV3 green digimon. Basically we can evo into him with Alliance, unsuspend it with Davis and Ken, EoA revive a rookie, and attack again with Alliance suspending the rookie we just revives. Then EoA again to revive a second rookie. We can revive Terriermon Assistant with the first effect to do the second attack with +5k, then revive BT3 Terriermon to finish the turn with a memory blocker. 

We can also Revive the memory blocker first, then attack suspending it to evo into the Imperials following the standard combo. You get the same value but your ending board finishes with the memory blocker (extra +1 card economy) and more checks done since you attacked twice. 

These are the main combo lines the deck has. There is still some territory to explore with the deck and I´m sure the decklist is still not fully optimized to BT12+EX4 meta, but the deck is still pretty fun to play and it´s quite good at practice. The most common matchups of BT12 are pretty winnable with this and the hardest matchups are the ones that can blow your small bodies in turn 2-3. This can be adjusted by including the EX4 dual tamer, but I invite you to test this deck and play this funny combo, yugioh-like deck!