You can cast any racial abilities in your macros. Most of them are best used when you're casting a series of high damage spells
or you're gaining a damage boost from one of your abilities. For example:
#showtooltip Vendetta
/cast Blood Fury
/use 13
/use 14
/cast Vendetta
This will cast the racial ability "Blood Fury" along with the "use" trinkets that might be equipped, then it casts "Vendetta". That would
be a major boost in damage dealt.
Another example would be:
#showtooltip Elemental Mastery
/cast Berserking
/use 13
/use 14
/cast Elemental Mastery
/cast Lightning Bolt
This is a good example of a non-damaging boosting racial used in a macro:
#showtooltip Rebuke
/cast Arcane Torrent
/cast Rebuke
Another for getting out of a stun lock and then stunning your enemy next to you (if you have a PvP trinket equipped):
#showtooltip War Stomp
/use 13
/use 14
/cast War Stomp
Engineers get some of their items with "use" abilities enchanted on them:
#showtooltip
/use 6 (belt)
/use 13
/use 14
/use 10 (gloves)
/cast Blood Fury
/cast Demon Soul