The server's own counts and lists

expressionstatistic <name> of <who>since 1.7.55

One of the game's own statistics for a player, online or not: "deaths", "jump", "play_one_minute", "mob_kills", "player_kills", "walk_one_cm" and the rest, as the game names them

set {_deaths} to statistic "deaths" of player
send "&7You have died &c%{_deaths}% &7times."

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expressionstatistic <name> of <who> for <thing>since 1.7.55

For the statistics that are kept for each block, item or creature: statistic "mine_block" of player for "stone", statistic "kill_entity" of player for "zombie". Without for, all of them added up

set {_stone} to statistic "mine_block" of player for "stone"
send "&7Stone mined: &f%{_stone}%"

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expressionall commandssince 1.7.55

Every command the server has, each with its slash, as a list

send "&7This server has %size of all commands% commands."

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expressioncommands of <who>since 1.7.55

The ones that player may use

set {_mine} to commands of player
send "&7You can use %size of {_mine}% commands."

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expressionall permissions of <who>since 1.7.55

Every permission a player has, as a list; permissions of <who> says the same

for each {_node} in all permissions of player:
    send "&7- %{_node}%"

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effectgive selection wand to <who>since 1.7.55

A golden axe that marks: left-click a block for the first corner, right-click for the second

give selection wand to player

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expressionselection start of <who>since 1.7.55

The first corner they marked, as a location; unset if they did not

command /makearena <name>:
    permission: op
    trigger:
        if selection size of player is not set:
            send "&cMark two corners with the wand first."
            stop
        create region arg.1 from selection start of player to selection end of player
        send "&aMade %arg.1%."

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expressionselection end of <who>since 1.7.55

The second corner

set {_far} to selection end of player

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expressionselection size of <who>since 1.7.55

How many blocks lie between the two, both included; unset until both are marked

send "&7You marked %selection size of player% blocks."

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effectclear selection of <who>since 1.7.55

Forget both corners

clear selection of player

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expressionsave structure <name> from <position> to <position>since 1.7.55

Keep everything between two corners in a file, as the game's structure blocks do

save structure "house" from selection start of player to selection end of player

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expressionplace structure <name> at <position>since 1.7.55

Put it back somewhere, its lowest corner at that place. rotated 90, 180 or 270 turns it

place structure "house" at player

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expressionstructure <name> existssince 1.7.55

A condition

if structure "house" exists:
    place structure "house" at player

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effectdelete structure <name>since 1.7.55

Remove the file

delete structure "house"

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expressionblock word <text>since 1.7.55

Chat with that word in it is starred, or kept back; a list blocks several

block word "badword"

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expressionunblock word <text>since 1.7.55

It may be said again

unblock word "badword"

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expressionblocked wordssince 1.7.55

The words that are blocked, as a list

send "&7Blocked: %blocked words%"

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Guide and examples

Syntax	Meaning
`statistic <name> of <who>`	One of the game's own statistics for a player, online or not: `"deaths"`, `"jump"`, `"play_one_minute"`, `"mob_kills"`, `"player_kills"`, `"walk_one_cm"` and the rest, as the game names them
`statistic <name> of <who> for <thing>`	For the statistics that are kept for each block, item or creature: `statistic "mine_block" of player for "stone"`, `statistic "kill_entity" of player for "zombie"`. Without `for`, all of them added up
`all commands`	Every command the server has, each with its slash, as a list
`commands of <who>`	The ones that player may use
`all permissions of <who>`	Every permission a player has, as a list; `permissions of <who>` says the same
`give selection wand to <who>`	A golden axe that marks: left-click a block for the first corner, right-click for the second
`selection start of <who>`	The first corner they marked, as a location; unset if they did not
`selection end of <who>`	The second corner
`selection size of <who>`	How many blocks lie between the two, both included; unset until both are marked
`clear selection of <who>`	Forget both corners
`save structure <name> from <position> to <position>`	Keep everything between two corners in a file, as the game's structure blocks do
`place structure <name> at <position>`	Put it back somewhere, its lowest corner at that place. `rotated 90`, `180` or `270` turns it
`structure <name> exists`	A condition
`delete structure <name>`	Remove the file
`block word <text>`	Chat with that word in it is starred, or kept back; a list blocks several
`unblock word <text>`	It may be said again
`blocked words`	The words that are blocked, as a list

command /makearena <name>:
    permission: op
    trigger:
        if selection size of player is not set:
            send "&cMark two corners with the wand first."
            stop
        create region arg.1 from selection start of player to selection end of player
        save structure arg.1 from selection start of player to selection end of player
        send "&aMade %arg.1%."

on blocked word:
    add 1 to {%player%.warnings}
    if {%player%.warnings} >= 3:
        mute player for 10 minutes because "language"

Structures need Minecraft 1.17.1 or newer. A structure may have up to 250,000 blocks (limits.structure-blocks); saving a large one makes the server wait. The files are the game's own and lie in the main world's folder, under generated/hyperscript/structures.
Blocked words are found however they are dressed up: b4dw0rd, b.a.d.w.o.r.d, baaadword. A word has to stand by itself, so blocking ass leaves class alone. word-filter in config.yml says whether the message is sent with stars (censor, the default) or not sent (block). Players with the permission hyperscript.words.bypass are left alone, and the list is kept through restarts.
The wand remembers its corners until the player leaves. It is recognised by a mark on the item, so one that is renamed still works and an ordinary golden axe does not.