Free your opponent's creatures from their cruel master's oppressing hand! Send them to punish their former employer! Give them proper jobs and decent food! Join the Union, we have fluffy pets!
You can always Threaten them, after all, you're the Union Inspector. By the way, as a legitimate Union representative, you have the powers to Harness by Force, if them creatures are too brainwashed by their "elite" employers, or if that Wrangle is at a stale point. Should you need, call for backup! The Captivating Crew always stationed at the Union is more than ready and willing to help our Inspectors!
Causing an Act of Aggression is also fair game. And you can always count on the regular Act of Treason. For some elusive or difficult to persuade creatures, simply start glaring at them. Glaring at creatures (and at people, too) works wonders in convincing them. Oh, and that Glaring Spotlight is also useful on the night shifts! If everything fails, you can always go sneaky and Hijack their work equipments. Lack of, or misuse of PPEs is, as you know, a punishable offence....
After being freed, tell them how wrongfully they've been treated. I'm positive that they'll want some revenge, and then it's time to send them to beat that tyrant.
Then, after a good beating, offer them some soup, from that delicious smelling Bubbling Cauldron. You can also offer them some decent, Union regulated jobs, like working at the Blasting Station or cleaning the Spawning Pit. For those creatures smart enough to count past 5, offer them a job a the High Market, where the can earn and save money for a well deserved trip to the fabled Diamond Valley. And now, the Union has adopted the pioneering techniques of HRM (some nonsense pet therapy), and we've got a cute, harmless, fluffy animal, like the Conquering Manticore over there, so that them creatures might relieve some pent up stress... Just remind them to not feed the animals, as it is Zealous Conscripts's job to do so.
Should your opponent's creatures prove too much stubborn, or should your arguments be to no avail, you can always warn them about the dangers of Lightning Bolt, and some Brimstone Volley, that may strike them while working. Those advice are valid for their employers too, and they may also beware of some Collateral Damage, of said natural phenomena.
And now, with the jolly Cult of Rakdos as a backup plan, we can enforce creature's rights even if some employers seem to have none under their villanious reign! We can call upon the Rakdos Guildmage to summon some goblin servants. For some fun time, we can count on the Rakdos Cackler. The Vexing Devil can instill shame on those employers, for not providing proper, Union regulated jobs to their creatures. The Ashenmoor Liege has come to enforce the rules. And, as with any cult, the Demigod of Revenge himself can be summoned, to punish those who mistreat and abuse! And, due Union's efficiency, all night operations can be safely done with the help of a spare Glaring Spotlight.
There you go. Another good day's work in the shoes of an MTG Creatures' Union Inspector!
v1.1:The Union has hit an all time high number of afilliateds! Now we are able to better serve and protect creatures from they cruel master's oppressing clutches!
v1.2:As more and more creatures realize the facts that they have rights, and that the Union is here to help them enforce said rights, we've been growing and growing our ranks! So much that we've made contact with some pretty friendly and totaly thrustworthy fellas from the Rakdos Cult. They too, think that creatures should be freed, and have a good time. In that aspect, we've made a gentleman's agreement with them, and now the Union can call in some of those cultists to help us spread the word!