Magic Mouth usually is used  to leave messages behind.  

This version works just the same as the original spell when a  Triggering event occurs the Magic Mouth Repeats its message.  However this version is equipped with a small portion of  the spell casting energies of the mage who cast it, thus it is able to utter "Command Words" for magical Items.   

For instance Grug The Scourge  -- Nasty Barbarian him was trying to sneak into a castle through the swears one night.  But a mage had laid ia silver strand of unicorn hair across the sewer tunnel and when that trip wire was engaged  " Zorcon's Trap Triggering Magic Mouth" Did it's thing,  speaking the command word of a wand of fireballs  conveniently mounted to the ceiling above the trip wire.  And poof Just like that Grug the Scourge, Became Grug the Cinder which is not nearly so intimating of a name.   Because you know the whole death thing. 

So if you have Barbarian  problems or whatever,  Ninja's maybe?  just  do your basic drop a ceiling  on them  or spiky pit bit... really kill them good with " Zorcons Trap Triggering Magic Mouth"  Your's roday for  only  12 GP or on Kryn SP  because steel is more valuable then gold there... N stuff