“[Choose a <clan> from your hand and discard it] When this unit is placed on the GC, you may pay the cost. If you do, choose one of your <clan>, and that unit cannot be hit until the end of that battle.”
Perfect Guard, Null Guard, Perfect Defense. This type of card has various names, yet serves the same purpose for everyone’s deck. The wall that cannot be broken no matter how much power your attack has. The Grade 1 that has 0 shield. A staple for every deck that wishes to be competitive.
The Null Guard, as I shall be referring it as, is a card that every deck in a competition use to increase their chances of victory. It is a way to prevent using up multiple cards in your hand to defend against an attack with massive power, such as Dragonic Waterfall after discarding a Grade 3 Kagero or Blond Ezel the turn his Limit Break was used. It is also a way to defend against one of the most annoying unit in the game, Silent Tom. With Tom’s ability to prevent your best defensive cards from guarding the attack, the Null Guard is the best way to save your hand, and sometimes even the game, when Tom has a critical trigger effect placed on him. It is because of this kind of card that even an overwhelmingly powerful attack can be stopped in its track.
Null Guards are Grade 1 units that have 6000 power, which is not a large number compare to most Grade 1 units. But the Null Guard is not meant to support an attack; it is the ultimate defender in your arsenal. And the cost for this defense is another card of the same clan from your hand. This means that those Grade 3s that are clogging your hand can be used for defense after all. Because Grade 3 have no shield points, it is important to reserve the Null Guards to discard the Grade 3s. That way you are using each card to the maximum potential you can use. Players also use their Null Guards to discard their draw triggers in their hand, since they lack offensive power and have a mere 5000 shield point. Decks like Oracle Think Tank or Bermuda Triangle, decks that draw cards alot, will play four Null Guard for maximum defense since they do not need to be concerned about low card count in their hand.
When you do have a low card count though, then having a Null Guard might actually hinder your defense rather than helping it. Still confused? Let us say you only have an intercept as your defense next turn before your drive check. Your opponent's front line has no boosters, so as long as you can get two cards with shields on them there is a chance you can survive the next turn. The twin drive shows another 5000 shield card and a Null Guard. When your opponent attacks, you realize that you can only defend two attacks for sure: intercepting the first attack and nullifying the second attack. That means you have to take the third attack. If that Null Guard was another 5000 shield card, you would have had a chance to defend yourself if there wasn't a drive trigger. That is why, in my opinion, playing three Null Guards is enough to handle most decks. There isn't too many decks that will always force out 15000 sheild to defend their attacks, and you do not want to be in a situation where two of the three cards in your hand are null guards; that can be just as bad as having two Grade 3 in hand sometimes.
I personally think that decks with crossrides do not need to run four Null Guards as well. Because they have the potential 13000 power vanguard, any attack less than 18000 power is easy to defend against and hardly any deck than make 23000 power rearguard. So having multiple 5000 and 10000 shield cards is more effective to defend than using a Null Guard in those deck, especially for Phantom Blaster Overlord since Nightmare Painter can put the Blaster Dragon into soul without crossriding it right away.
Now that I covered some information about Null Guard, should players use three or four of them in a deck? That has a few factors into it depending on deck style, clan, etc., but ultimately it is your choice. Players have build budget decks that do not play a single Null Guard because the player simply could not afford them, and still play well against completed deck. Mixed decks can not use Null Guards at all since they usually will not have space for it, and Null Guards do not work for different clans, so it is hard to determine what clan the Null Guard should be when you have two different clan for your Grade 3 line-up. Kagero and Spike Brothers can use their starter to seach our their deck for their Null Guard, so they can play three and guarantee one at least every game. A deck that plays 8 or more draw triggers should play four to make up for the lack of 10000 shield cards in their deck, and crossrides can make do with three. Overall though it is the player's choice on the number of Null Guards in their deck.
The big question that people want to know is how to get around the Null Guards? Certainly if the player manages to use all three or four of his null guards to defend againt your biggest attack power it will be tough to defeat. But there are a few ways to go around them. Stand triggers and effects to stand such as Asura Kaiser are the most direct way to get around null guards, as Null Guard stop only one attacks. Muliple attacks can force out more shields as well as forcing the player to wonder if you will get a critical or stand trigger in your drive check to win. Problem is that very few deck pay stand triggers, even less when it is against the more competative people. And not too many people play Asura Kaiser combine with the two Death Armies we have at the moment. Aqua Force has the ability to do multiple attacks but it is not yet released in the TCG. Using units that have a skill that activates when landing an attack can be a good way to force out those Null Guards. Player of the Holy Bow, Viviane and Spring Breeze Messenger are two such cards that can force out a Null Guard because of that chance to superior call a Dindrane, Lop Ear Shooter, or heaven forbids, Pellinore. Units that have particular skills to seal off a method to defend, such as Silent Tom and Toxic Trooper, can force out a Null Guard due to their skill to prevent Grade 0 from guarding and interception from working respectively. Another Aqua Force card, Glory Malestorm, has an Ultimate Break (Limit Break that activates at 5 damage) that prevents Grade 1 units an higher from defending. And then dealing a lot of damages fast will force out the Null Guard fast to defend the damages, especially when your opponent thinks you play a 12 critical deck.
So is it impossible to defeat an opponent that plays four Null Guards? Not really. Chances are he or she will ride a Null Guard once in a while because of no other Grade 1 in hand, and there's a decent chance one will be hit in the damage zone. Having more perfect shields increases the chances of you getting to use some of them at the very least, but it also increase the chances of one or two of them being wasted in one way or another.