The most current version of the Magic Comprehensive Rules is always available at www.wizards.com/magic/comprules.
What's an Equipment, anyway?
Artifacts that have the subtype "Equipment" are a special kind of artifact. Generally, an Equipment doesn't do anything unless it's attached to a creature. Equipment works in much the same way as local enchantments, but there are some important differences. The biggest differences are (1) an Equipment doesn't equip anything when it comes into play, and (2) an Equipment stays in play when the creature it's equipping leaves play.
Here's an example of an Equipment, Loxodon Warhammer. Note that its subtype is "Equipment." That's how you know what it does. Also, it has the "equip" keyword ability. You use the equip ability to attach Equipment to creatures.
The equip keyword ability is pretty straightforward. The equip ability can target only a creature you control. It's okay if Equipment gets onto a creature your opponent controls (such as via your opponent playing Confiscate on your equipped creature), but you can't do this using the equip ability. Also, you can play the ability only any time you could play a sorcery. The cleverest combat trick you can do with Loxodon Warhammer is attaching it to one of your creatures and smashing your opponent's face with it.
You can also move an Equipment you control from one creature to another by playing its equip ability. If you control two Grizzy Bears, you could attach the Warhammer to one, attack with it, then, in your second main phase, play the equip ability a second time to move the Warhammer to the other, so that you've got a 5/2 creature ready to block. You can't just move an Equipment off a creature, though – you have to move it onto a different creature you control.
The biggest difference between Equipment and local enchantments is that Equipment stays in play when the creature it's attached to leaves play. In fact, Equipment doesn't really care too much about what happens to the creature it's attached to. If an equipped creature leaves play, the Equipment “drops off” and stays in play unattached. The same is true if an equipped creature can no longer be equipped (if it gains protection from artifacts, or stops being a creature, for example).
How does Equipment interact with other cards?
Equipment can do a whole variety of different things. You'll find Equipment that do all the common things that creature enchantments do. Plus, because Equipment stays in play when the equipped creature leaves play, you'll find some more interesting things that it can do. The Warhammer does three different things. It changes power and toughness, gives a keyword ability, and gives the creature a triggered ability.
Equipment can't be attached to a creature with protection from artifacts. The equip ability can't target a Yavimaya Scion, because the ability is from an artifact source. If you've equipped a Jeweled Spirit with the Warhammer, and you then play its ability to give itself protection from artifacts, the Warhammer will fall off back into play (remember, Equipment doesn't go to the graveyard if it can't be attached to a creature). It won't reattach itself when the Spirit loses protection from artifacts at the end of the turn. You'll have to wait for the effect to end, and then play the equip ability again.
The equip ability can't target a Gigapede, because it can't be the target of spells and abilities. There's no real way around this, even though being untargetable wouldn't cause the equipment to fall off. If the Warhammer is equipping a Glimmering Angel, making the Angel untargetable won't make the Warhammer fall off.
You can attach the Warhammer to a Chimeric Idol as long as you animate the Idol before you play the equip ability. At the end of the turn, the Idol will stop being a creature, and the Warhammer will fall off back into play.
What's the strangest thing that could happen?
Most of the strange things that can happen in the Magic game don't have anything to do with Equipment. But there are a few more things about Equipment that you might not know yet.
Gaining control of an equipped creature doesn’t give you control of the Equipment on it. The Equipment remains attached to the creature, but only the Equipment’s controller can play its equip ability.
An Equipment that becomes a creature can't be attached to a creature. If you play Karn's Touch on an attached Equipment, it becomes unattached and stays in play as a creature. Of course, you wouldn't be playing Karn's Touch in your deck, now would you? You can play the equip abilities of Equipment that are creatures, but that ability won't do anything at all when it resolves.
An Equipment that loses the subtype Equipment can't be attached to a creature. If it stops being an artifact, it'll lose its artifact subtypes, including "Equipment." If an attached Equipment loses the subtype "Equipment," it becomes unattached and stays in play.
If an Equipment is being moved from one creature to another and the creature it's moving to can't be equipped, the Equipment stays where it is. If the Equipment was attached to a creature when the equip ability was played, the Equipment doesn't become unattached.
Why do I need to know any of the boring stuff in this section?
You don't. But, if you want to know exactly how the rules for Equipment work, read on.
The official rules for Equipment are as follows:
212.2g Some artifacts have the subtype "Equipment." An Equipment can be attached to a creature. It can't legally be attached to an object that isn't a creature.
212.2h An Equipment is played and comes into play just like any other artifact. An Equipment doesn't come into play attached to a creature. The equip keyword ability moves the Equipment onto a creature you control (see rule 502.33, "Equip"). Control of the creature matters only when the equip ability is played and resolved.
212.2i An Equipment that's also a creature can't equip a creature. Equipment that loses the subtype "Equipment" can't equip a creature. An Equipment can't equip itself. An Equipment that equips an illegal or nonexistent permanent stops equipping that permanent, but remains in play. (This is a state-based effect. See rule 420.)
212.2j The creature an Equipment is attached to is called the "equipped creature." The Equipment is attached to, or "equips," that creature.
212.2k An Equipment's controller is separate from the equipped creature's controller; the two need not be the same. Changing control of the creature doesn't change control of the Equipment, and vice versa. Only the Equipment's controller can play its abilities. However, if the Equipment adds an ability to the equipped creature (with "gains" or "has"), the equipped creature's controller is the only one who can play that ability.
The official rules for the equip ability are as follows:
502.33a Equip is an activated ability of artifact Equipment cards. The phrase "Equip [cost]" means "[cost]: Move this Equipment onto target creature you control. Play this ability only any time you could play a sorcery."
502.33b For more information about Equipment, see rule 212.2, "Artifacts."
502.33c If an artifact has multiple instances of equip, any of its equip abilities may be used.
The following rule has been added the protection ability:
502.7d A permanent with protection can't be equipped by Equipment that have the stated quality. Such an Equipment stops equipping that permanent, but remains in play. (See rule 420, "State-Based Effects.")
Several other rules have been modified to cover Equipment cards; those rules are not listed here.Send questions and comments to firstname.lastname@example.org.