Enchantments of your own

structureenchantment <name>:since 1.7.17

At the left margin. One to four plain words, not the name of one of the game's enchantments

enchantment lifesteal:
    max level: 3
    on hit:
        add {_level} to health of player

Try it

expressionmax level: <n>since 1.7.17

The highest level that counts, 5 unless you say otherwise; an item with more acts as if it had this many

enchantment thorns of fire:
    max level: 2
    on hurt:
        ignite attacker for 3 seconds

Try it

eventon hit:since 1.7.17

Runs when a player hits something with the item in their main hand. victim, damage and the rest are there as in on hit:

enchantment lightning:
    on hit:
        if chance of 20%:
            strike lightning at victim

Try it

What this event gives a script

Placeholder	Short form	Type	Meaning
`%event.attacker%`	`attacker`	text	Who dealt the damage: a player's name or a mob type such as zombie. For an arrow or other projectile this is whoever shot it. Unset for damage with no attacker, such as falling
`%event.victim%`	`victim`	text	Who was hurt: a player's name or a mob type
`%event.damage%`	`damage`	number	Damage actually taken, after armour and effects; 2 is one heart
`%event.cause%`	`cause`	text	Why: FALL, FIRE, ENTITY_ATTACK, PROJECTILE, DROWNING, VOID and so on
`%event.entity%`	`entity`	text	The victim's entity type, e.g. player or zombie
`%event.location%`		location	Where the victim is
`x of event's location`		number	The x of %event.location%, as a number
`y of event's location`		number	The y of %event.location%, as a number: how high it is
`z of event's location`		number	The z of %event.location%, as a number

Can be cancelled: Yes
player is: The victim if a player was hurt; otherwise the attacker if a player dealt the damage; otherwise nobody

More about on entity damage:, with a box to try it in

eventon hurt:since 1.7.17

Runs when a player is hurt by someone while wearing the item, or holding it in either hand

enchantment dodge:
    on hurt:
        if chance of 10%:
            cancel event
            send "&7Dodged!"

Try it

eventon block break:

Runs when a player breaks a block with the item in their main hand

enchantment prospector:
    on block break:
        if event.block is "stone":
            if chance of 5%:
                give player 1 gold nugget

Try it

What this event gives a script

Placeholder	Short form	Type	Meaning
`%player%`	`player`	player	The player the event is about; use it wherever a player is expected
`%event.block%`	`block`	text	The block type, e.g. diamond_ore
`%event.location%`		location	Where the block is
`%event.drops%`		list	The items the block will drop with the tool in the player's hand
`x of event's location`		number	The x of %event.location%, as a number
`y of event's location`		number	The y of %event.location%, as a number: how high it is
`z of event's location`		number	The z of %event.location%, as a number

Can be cancelled: Yes
player is: The player breaking the block

More about on block break:, with a box to try it in

Guide and examples

A script can make up an enchantment: a name, and what happens when an item that carries it is used.

enchantment lifesteal:
    max level: 3
    on hit:
        add {_level} to health of player

command /vampire:
    trigger:
        give player 1 iron sword enchanted with lifesteal 2

Line	Meaning
`enchantment <name>:`	At the left margin. One to four plain words, not the name of one of the game's enchantments
`max level: <n>`	The highest level that counts, 5 unless you say otherwise; an item with more acts as if it had this many
`on hit:`	Runs when a player hits something with the item in their main hand. `victim`, `damage` and the rest are there as in `on hit:`
`on hurt:`	Runs when a player is hurt by someone while wearing the item, or holding it in either hand
`on block break:`	Runs when a player breaks a block with the item in their main hand

Inside those blocks {_level} is the level on the item, and player is whoever holds it.
An item gets it the way it gets any other: enchanted with lifesteal 2, alone or among the game's own (enchanted with sharpness 5, lifesteal 1), in give, in an item <name>:, or with enchant tool of player with .... Any script can use an enchantment another file defines.
The game does not know these enchantments. An item shows one as a grey line at the top of its description (Lifesteal II) and has no enchantment shimmer because of it; add glowing for that. They cannot be had from an enchanting table or combined on an anvil.