A-Counter

A-Counter means "Alien Counter". Certain card effects depend on these to exist on opponent's monsters to work, and when an "Alien" monster battles with a monster that has an A-Counter, the monster with the A-Counter loses 300 ATK and DEF during Damage Calculation only.

Note that, due to the ruling on A-Counters, you need a monster that specifically mentions the ATK and DEF decrease on the field to use that effect. However, it's cumulative, allowing for drastic ATK and DEF reduction should multiple monsters on the field mention the ATK and DEF reduction.

Lore wise, A-Counters take the form of Corruption Cell "A", or A-Cells, which resemble a gelatinous blob of flesh with a tubular "mouth" and a tail. Interplanetary Invader "A" is also an A-Counter, apparently having evolved legs and the ability to mind control without the need of another Alien.

Also See: Aliens.

Here's a list of cards that use A-Counters:

• "A" Cell Breeding Device
• "A" Cell Incubator
• "A" Cell Scatter Burst
• Alien Grey
• Alien Hunter
• Alien Hypno
• Alien Mars
• Alien Mother
• Alien Psychic
• Alien Revenger
• Alien Warrior
• Alien Skull
• Alien Telepath
• Brainwashing Beam
• Cell Explosion Virus
• Corruption Cell "A"
• Cosmic Horror Gangi'el
• Cosmic Fortress Gol'gar
• Detonator Circle "A"
• Interdimensional Warp
• Mass Hypnosis
• Planetary Contamination Virus