To understand Link Joker, you must understand the their ability to devour, the clan's definitive mechanic, "Lock." A Locked card is turned face-down, rendering it completely unusuable, and is no longer treated as a rearguard. Consequently, Locked cards cannot be retired or have new units called over them. The clan of a Locked unit is also negated in the process, so that Locked units effectively cease to exist but prevent their rearguard circle from being used. In this way a destructive strategy is created that breaks the rearguard circle, preventing units like Alfred from drawing power out of those circles, while also stopping those rearguards' skills from being used and obstructing attacks. However, the power of Lock is finite. At the end phase of the owner of the Locked card's turn, the Lock will open and the unit will be released, so the skill is not as permanent as the straight retire abilities of clans like Kagerou or Narukami, but if played well it can be even more effective to destroy rearguard-centric decks and mitigate the attacking power of other strategies.
By Locking the opposing vanguard booster and one of the frontrow rearguards, Infinite comes more than halfway to achieving Link Joker's ideal field setup, and Dust Tail can complete it. Since Dust Tail has no frontrow or backrow restrictions, it can easily complete the strategy by Locking the remaining frontrow unit. By executing this strategy, both rearguard columns are prevented from attacking for a turn while the vanguard can only swing independently, a feat that only specific one-man army units and other break rides are really able to measure up to. This is while Infinite attacks them in the range of 23~31000 power and makes specific combos with cards from BT12, forcing the opponent to drop more cards for one turn while you conserve on theirs. This provides a breather turn after you've hit limit break to stabilize your position and capitalize on these characteristics as much as possible to try and snowball the effects of Lock.
This is where their other primary grade 3 comes in. From BT12, Nebula Lord Dragon is the commander of Link Joker's advance guard, the Star-vaders. His counterblast 2 is restricted to Locking an opponent's backrow unit, but the real attraction of this card is his limit break, a continuous skill that gives all frontrow Link Joker units +3000 power for each of the opponent's Locked cards in play. Comboing this with Infinite Zero, that's a +6000 power boost that will easily put Nebula in the 17~22000 power range depending on his booster, and rearguard Star-vader attackers at 18000 power before boosting. If Dust Tail is factored in, you can have the perfect field Lock of left and right attackers along with the opponent's vanguard booster for a +9000 boost to the front row. With the clan's standard grade 2 subclan attacker, Unrivaled Star-vader Radon, you can add this to a 12000 power swing to make 21000 power rearguard columns and with any kind of reasonable booster Nebula Lord himself will be in the range of 26~28000. Realistically speaking however, the three Lock ideal is out of reach. It's more practical to save Dust Tail for the next turn, using Infinite's break ride to Lock 2, and then when that turn does come around use Nebula Lord to Lock the vanguard booster and greenlight Dust Tail's skill to Lock a frontrow unit again. In general the number of turns you can prolong a series of Locks are more important than the quantity of units that you are able to Lock.
Nebula Lord also has specific combos with BT12's grade 2 and 1 units, Evil Claw Star-vader Niobium and Demonic Claw Star-vader Lanthanum. These are base 9000 and 7000 units that each get +2000 power when a card is Locked. These skills will stack with Nebula Lord's, so that in the Lock 2 example a Lanthan boosting a Niob will together swing for 30000 power, and it also gives Lanthan a specific combo with Radon where in that same example Lanthan's 11000 power and Radon's base 12000 with Nebula Lord's +6000 limit break would make a 29000 power line, functionally the same in the BT10-on format where base 10000 vanguards are rare. For these reasons Niob and Radon are frequently interchangeable on the frontrow, but protecting Niob on the opponent's turn becomes a priority, since it's beneficial for them to try and destroy Niob before Infinite Zero's break ride skill can go off.
We've already established that the innate value of Lock is conservation, but conservation by itself is not a game determining effect. What makes Link Joker dangerous is not Lock, but all of the extraneous effects that can be derived from it through limit breaks. Nebula Lord is only the first of many, specifically using it to bring out pure force, but what should be apparent here is that by himself he can only carry that power boost for a single turn. Past a certain point in the game, if you cannot do something every turn, it is rarely worth doing at all. So Link Joker's secret is that the clan wants to keep riding Infinite Zero for as many turns as possible, prolonging the effects of Lock, swinging with three rows for ~23000 power while the opponent is restricted to using half of a vanguard column and one rearguard line, and go into Nebula Lord for the endgame only when there are no Infinites remaining in hand. The entire stability of Link Joker prior to BT13: Catastrophic Outbreak rests on Infinite Zero Dragon, so you should plan your deck accordingly. Link Joker is a slow, late game centric clan which needs to go through as many cards as possible to gather as many Infinites as possible, and this is part of why its initial reception in Japan was so lukewarm. To set up its gameplan effectively, running between five and seven draw triggers with seven or fewer critical triggers will help you go through more cards and slow the opponent down with defensive checks. This is supported by the results of the 2013 tournament season, where the 5~7 draw concept was effectively proven at FC2013 Tokyo, July 2013 Fateclock VGCS, and Chiba VGCS. Based on this history, six draw is a recommended start for BT12-on.
The opposing side of Nebula Lord is that while the deck is very dependent on Infinite, it's also one of the more enduring Link Joker builds. Even with the eventual introduction of unlock skills that can break the clan's spell, the fact that everything Nebula and Infinite are trying to do is happening inside of their own turn means that there is no hard counter to the massive power boosts they can bring into play. Dismantling Lock only cuts out half of their strategy, while the remaining half could easily carry a deck on its own.
For supporting units outside of standard subclan attackers and units that power up by Locking cards, you should consider the grade 2 Star-vader Mobius Breath Dragon, another of the trial deck exclusives. Mobius Breath can only Lock one of the opponent's rearguards when his attack hits and he's also on the vanguard circle, but this midgame Lock is considered extremely valuable because it can either disrupt the opponent's strategy by taking one of their boosting or attacking units out of play and let you conserve more early on to slow down rush decks like Spike Brothers, or counter first vanguard skills like Linchu and Wingal Brave. If the opponent is running grade 3 searchers this can even cause them to become gradelocked, and it will also trigger Niobium's skill for early game attacks. Even if the opponent defends the attack, since Mobius will strike in the range of 14~16000 power after boosting it becomes a situation where the opponent cannot win since they're forced to either permanently give up cards earlier by guarding while reaching limit break more slowly or have their strategy disrupted. There is a lot of room to doubt what's otherwise an unskilled 9000 power unit outside of these specific scenarios, but like the 5~7 draw strategy Mobius has been repeatedly proven in VGCS tournaments. The card is generally recommended to be run at 3 copies.
Outside of the mainstream Link Joker deck, there are several alternative builds available. Dark Band Dragon is the other Star-vader boss card standing opposite Nebula Lord in that it's a more strategic deck, benefiting from the same base of support but with a different end goal. As the prototypical Link Joker grade 3 introduced early on in preview material and released in English ahead of the other cards by way of promo packs, Dark Band sits at a lower 10000 base power but gets +3000 if you have more rearguards than the opponent, which with their base 8000 grade 1 Binary Star can make for a very simple 21000 line, or with Aurora Eagle who shares his activation conditions Dark Band can get a total +10000 power boost and swing for an anticrossride 23000. The way that Dark Band fuels these skills is with his limit break, counterblast 1 "Star-vader" to Lock one of the opponent's backrow rearguards. Because cards that are Locked do not exist, filling your own field while Locking even one of the opponent's rearguards will activate these conditions and happily coincide with Lanthan and Niob's skills. Since Dark Band Dragon's especial counterblast is a cheaper cost overall, and as a Star-vader Aurora Eagle can easily replace the non-Star-vader Binary Star in the deck, you can easily build a pure Star-vader deck focused on Infinite Zero into Dark Band to continually Lock the opponent's rearguards and activate those power up skills, using multiple break rides as in the Nebula Lord deck and when they wear off going for Dark Band into Dust Tail. For the final endgame, Dark Band can CB3 to Lock the entire back row, greatly weakening the opponent at a crucial point in the fight. This strategy loses the supplementary power boost that makes the Nebula Lord build so definitely strong, but the only specific setback it faces in comparison to that card is falling harder to the unlock skills of BT14-on.
Outside of the Star-vaders, Link Joker's options are presently limited but not without merit. Knight of Entropy is the clan's Garmore clone, a base 10000 grade 3 vanguard with a +5000 power on-attack limit break, and his counterblast 2 Locks one of the opponent's rearguards to achieve card advantage rather than pull cards from the deck like preceding Garmore-type units, which does give you more room to repeatedly ride Entropy without a reprising loss in advantage even though this is a very limited means of controlling the field and will generally only happen twice per game once Dust Tail is accounted for. A more alluring grade 3 is Schwarzschild Dragon, their second RRR and clanwide boss card. As the original enemy to contact Cray and the one who sealed the three heroes, Schwarzschild has a suitable base of support to work off of. This Cyber Dragon is the key grade 3 for Link Joker's evolving ride, and comes with all the trappings of third season-era card evolution; instead of Dust Tail Unicorn, the Schwarzschild deck uses the base 4000 Microhole Dracokid as its first vanguard. There are benefits to using Dust Tail with the build, but we'll get into why it's difficult to use something other than Microhole in a bit.
By riding the grade 1 Gravity Ball Dragon over Microhole Dracokid, you can look at up to seven cards from the top of the deck for either Schwarzschild or the grade 2 Gravity Collapse Dragon. Even if you can't find Gravity Collapse, as long as you can ride another grade 2, his skill will search another seven cards for Gravity Collapse and try to superior ride the card. Since Link Joker doesn't make use of many soulblasts, it's not as beneficial as in Genesis, but the real benefit to riding Gravity Collapse is that as long as the corresponding grade 1 and 2 units are in the soul, you can Lock any of the opponent's rearguards. The guaranteed Lock is an improvement over Mobius Breath, but the skills are fairly incomparable because Gravity Collapse does not have the same properties of a high-pressure midgame swing, instead shutting down one part of the opponent's turn outright. This is also one of the reasons that running Dust Tail in Schwarzschild is difficult. Gravity Collapse is necessary for Schwarzschild to become a base 11000 unit, and you would naturally want to use Gravity Collapse's skill to take maximum advantage of the deck's characteristics, but this requires both the grade 1 and grade 0 to pull off. VG-BT13: Catastrophic Outbreak introduces cards that can allow for both to be used, but for the time being Microhole is the recommended first vanguard.
Finally, Schwarzschild Dragon itself is the mastermind behind the Liberation War and the one who originally sealed Blaster Blade, Blaster Dark and Dragonic Overlord. His skills are appropriately powerful. Schwarzschild is the only Link Joker capable of Locking three of the opponents' rearguards simultaneously, achieving the ideal gameplan of shutting down both frontrow rearguard circles and the vanguard booster. The catch is that his cost ensures that this is only a once per game play. Counterblast 3 is not so hard to pay in a dedicated Schwarzschild deck because he is the only card in the deck that uses counterblast, but you also have to persona blast to do so, necessitating a second copy of Schwarzschild to already be in hand. If you don't already have it, Schwarzschild has a supporting on-ride skill that lets you look at up to five cards from the top of the deck for a copy of him for just counterblast 1, and this combined with Microhole makes getting that second copy in hand much easier. The most important aspect of the card is the timing of the persona blast; to make the most of Schwarzschild, it's best to repeatedly break ride Infinite over Infinite to power up Lanthan and Niob for several turns, then on the turn after you've finally ridden Schwarzschild and the opponent's Locks have come undone, use the persona blast to make them go through a turn of zero resources. Since as a bonus the skill gives +10000 power and +1 critical to the Cyber Dragon, and the Lock 3 will give his supporting rearguards +6000 power, this forces the opponent to drop in the vicinity of 6~9 cards at a point when they should already be starved for resources from guarding intense earlier attacks, Schwarzschild's limit break is a skill that gets stronger the later in the match that it is used. The card rewards patience and utilitarian play. If you are forced to ride Schwarzschild before Infinite, it is better to try and re-ride into Infinite Zero and see if you can't get two of the remaining Schwarzschilds later on than it is to try to go all-in with the persona blast early. None of the Link Joker builds rush in the way that Spike Brothers or Nova Grappler can, and in fact their slowness in the BT12 format is their primary weakness alongside their general lack of a late game plan if resources are squandered. You need to be acutely aware of the fact that once Schwarzschild's persona blast has gone off, that no more skills will activate for the rest of the game after that point. The costs for Link Joker's Black Shield are designed to be easy to pay so that the cardfighter that can pace themselves will have an advantage over the fighters that cannot.
Overall Link Joker is a strategic midgame deck that can fight with explosive power on key turns, but is greatly hindered by the lack of active skills prior to turn 4, overdependence on Infinite Zero Dragon to base its strategies out of, and not being able to strike back effectively against early aggression. The clan rewards veterans and studious cardfighters who understand the characteristics of each deck as they face it, to know which rearguards are important Lock targets and how different boss cards can respond to the loss of their field. There is good reason that it took so long for it to catch on in its native country, but continued to endure to this day once it had. Later sets will revise Link Joker's strategy to counter some of its more serious weaknesses while introducing both alternate play styles and legacy support for the older decks; and for now, the invasion begins February 7th.