Unmount/cast spell/Mount
to add something nice to the TE i combined some terms to create a useful Macro, cause i dont found something useful like this
Here i used Charge to enter combat on mount, replace with any other spell you want. The actionbutton is the one, you placed your Mount, like explained on top of topic.
/script CastSpellByName("Charge()")
/run UseAction(26)
its not perfect but works.