Variables

/variable <name> {<value>}   (or /var)
/variable                    lists your variables
/unvariable <name>           removes one
/add <name> <number>         adds to a variable (1 if no number)
/echo <text>                 shows text to you only

@name anywhere in a command you type, an alias or a trigger is the variable's value (@@ is an "@"):

/var target {big orc}
kill @target
/al k {kill @target;bash @target}

A trigger can keep what it saw:

/ac {You get (%d) gold coins} {/add gold %1}
/echo Gold so far: @gold