Intermediate Gameplay FAQ: Introduction to Union Monsters

Union Monsters can be recognized by the fact that, where on an ordinary Effect Monster it would read 'Effect', Union Monsters have 'Union'. Cards such as "Worm Millidith", "Dark Necrofear", "Kiseitai" or "Armory Arm" act as Equip Spell Cards but do not have the text designating them Union Monsters; the latter of the forementioned four can even become a monster again.

Union Monsters are a special type of Effect Monster with (Type)/Union in their card text. They can function like an Equip Spell Card, and thus become vulnerable to cards that destroy Spell Cards, such as "Mystical Space Typhoon". They equip to the host Monster their text designates and generally grant it additional strength, such as an increase in ATK/DEF. Earlier Union Monsters destroy themselves to protect the host Monster if it would be destroyed by battle while equipped. More recent Union Monsters, though, such as "Heavy Mech Support Platform", "Spirit of the Six Samurai" and "Armored Cybern", also protect the host Monster from any kind of destruction.

Union Monsters can either Equip or Unequip to the host once per turn with their own Effect, given they are on the field. Additional cards, such as "Formation Union" and "Combination Attack" allow them to Equip and Unequip alternatively. Some Union Monsters fuse with their hosts, e.g. "V-Tiger Jet" and "W-Wing Catapult" to form "VW-Tiger Catapult" or "Dark Blade" and "Pitch-Dark Dragon" to form "Dark Blade the Dragon Knight". The Union Monsters introduced the XYZ Archetype (which would later become the VWXYZ Archetype), which had a new way of summoning their Fusion Monsters; this fairly unorthodox method involves banishing the Fusion Material Monsters to Special Summon, through a process similar to Contact Fusion, the Fusion Monsters from the Extra Deck.

After a prolonged absence, Union Monsters have made a comeback in Structure Deck 18: Machiners Command, which introduces a number of new Union Monsters, including "Machina Gearframe", with the highest ATK of any level 4 or lower Union Monster in the game, and "Machina Peacekeeper", who can search another Union Monster out of your deck when destroyed, whether in monster or Equip Card form. While neither grants anything to their equipped monster besides destruction protection, their uses outside of being equip cards are a great asset to decks that incorporate Union Monsters.

Several Union Monsters have also been included in the brand new Vylon Archetype.

Trivia
Following their release Union Monsters have taken a notable focus to combining with Machine type Monsters over other types, also becoming dominantly Machine-type Monsters. Examples of this include "Machina Peacekeeper", "Machina Gearframe", "Heavy Mech Support Platform", "Oilman" and the VWXYZ series.

Currently, there are no Union Monsters with more than 2000 ATK or DEF.

Example