Alien

The Aliens are a series of Reptile-type cards introduced in "Power of the Duelist", with further support added in "Cyberdark Impact", "Strike of Neos", "Force of the Breaker, "Tactical Evolution, "Gladiator's Assault", "Crimson Crisis" and "Raging Battle". Alien decks focus heavily on the use of "A-Counters", which weaken opposing monsters battling Aliens and allow the Alien user to take control of them. This is one of the first true Reptile archetypes and one of the only archetypes that focuses this heavily on manipulating the opponent.

=Playing style= Aliens focus on manipulating the opponent rather than strengthening themselves. They have a wide range of lower-level monsters that can be used to oppress or manipulate the opponent but are lacking at higher levels; however, the ability to take control of an opponent's strong monster more than makes up for this deficiency. That being said, the new cards from "Crimson Crisis" have made aliens much stronger due to the powerful field-clearing effect of "Cosmic Fortress Gol'gar" and the rapid A-Counter distribution of "Alien Overlord", as well as the devastating force of "Planet Pollutant Virus", which wipes out any of your opponent's monsters without A-Counters and infects any they summon for the next three turns.

Aliens are at their weakest against opponents capable of either summoning overwhelmingly powerful monsters early before they can be weakened by A-Counters or against opponents who can remove their monsters from the field faster then usual(most monsters maitain a field presence of 2-3 turns usually(notincluding Gladiator Beasts), which is often more then enough time for Aliens to distribute a fair amount of A-Counters) or flip them face-down again, such as a Rock-based deck or the popular "Gladiator Beasts". More less is that they lose their field control if an opponent controls "Skill Drain", which strips them of their abilities. No monster in the Alien archetype has over 2600 ATK, and the two strongest monsters in the archetype ("Cosmic Horror Gangi'el" and "Cosmic Fortress Gol'gar") technically do not count as "Aliens", so they gain no personal benefit from the weakening effect of A-Counters during battle. An Alien user needs to be aware to rely as much upon their "weaker" monsters as their stronger ones in order to prevail.

However, Aliens do possess a relatively large number of low-level beatdown monsters ("Alien Warrior" and "Alien Shocktrooper"), each of which are powerful enough to devastate your opponent with little help. "Alien Warrior" in particular will weaken opponent monsters with A-Counters on them, effectively allowing it to destroy powerful cards such as Jinzo and the Monarchs; and, in the event that "Alien Warrior" is destroyed, will distribute a good number of A-Counters to ensure that whatever follows will have a distinct advantage.

=Possible Combos=

Combo 1
This combo should be used only when your field is empty of monsters and you really need a way to get rid of your opponent's monsters fast.

For this combo to work, your opponent must have at least two monsters, one of them with at least two A-Counters. Remove two A-Counters from the field to Special Summon "Alien Overlord", then activate his effect to distribute A-Counter(s) amongst your opponent's monster(s) (each of your opponent's monsters should only have one A-Counter on each of them. Activate "Mysterious Triangle" to destroy one of your opponent's monsters (it is better to destroy the weakest monster, but if necessary you can destroy the strongest monster instead) and Special Summon "Alien Hypno" from your deck. Normal Summon "Alien Hypno" to gain its effect, then use its effect to take control of three of your opponent's strongest monsters that each have only one A-Counter on them. Most likely this will end up leaving your opponent's field empty. During the End Phase, all of the monsters that you took control of with "Alien Hypno" will be destroyed when each of the single A-Counters on them are removed. Since both "Mysterious Triangle's" effect of destroying the Special Summoned monster during the End Phase and the activation of Alien Hypno's effect also activated during the End Phase, you get to choose which effects resolve first. "Alien Hypno's" effect should be chosen as Step 1 and "Mysterious Triangle's" effect as Step 2.

Combo 2
This combo requires one "Alien Dog", one "Alien Overlord" and one Level 4 or lower Alien in your hand and at least one face-up monster one your opponent's side of the field. Normal Summon one Alien, Special Summon "Alien Dog" and place two A-Counters on your opponent's monster(s), then remove those two A-Counters to Special Summon "Alien Overlord". This combo works as a effective way of swarming the field quickly and gaining the field advantage you need easily.

=Weaknesses= The two major weaknesses Alien decks have are "Gladiator Beast" and "Lightsworn" decks. Because "Gladiator Beasts" and "Lightsworns" often swarm quickly, Aliens will have a hard time keeping up with the fast pace of the two decks. This may no longer be the case with the release of the"Raging Battle" booster set, which features "Alien Dog".

=A-Counters=

Putting A-Counters on opposing cards is essential to the success of Alien decks, as Aliens generally have no extremely powerful monsters other than "Cosmic Horror Gangi'el" and "Cosmic Fortress Gol'gar".

Since counters cannot be placed on face-down monsters, generally the best way to ensure that A-Counters can be used against the opponent is to use "Light of Intervention", though note that doing so negates much of the usefulness of "Alien Grey". Another use for "Light of Intervention" is that when Tribute Summoning "Flying Saucer Muusik'i" it can be Summoned in face-up defense position, creating a temporary barrier and allowing you to use its effect during your next Draw Phase. Other alternatives include "Ceasefire" or "Swords of Revealing Light".

According to the current ruling on A-Counters, they do not reduce the ATK and DEF of monsters battling Alien monsters if no cards exist on the field that mention that effect. This means that if you only control an "Alien Shocktrooper", for example, your opponent's monsters will not be weakened, no matter how many A-Counters are on them. The upside to this ruling is that these effects accumulate, so if you control two "Alien Warriors", the opponent's monsters will be twice as weakened for every A-Counter on them.