Such a pet could be pay walled, like a special pet - Droid or Steam exclusive pets.
Bonuses:
Increase the tributes collected by 10% and increase the tribute chances per kingdom by 5%. ((existing chance + 5)%)
Increase the tributes collected by 20% and increase the tribute chances per kingdom by 10%.
Increase the tributes collected by 50% and increase the tribute chances per kingdom by 25%.
These would be very powerful as the number of gems you get from tributes goes up with the more tributes you get I think they would be worth it to buy! Especially if you are active a lot and collect a lot of tributes per day a couple extra gems per hour adds up fast.
This pet would be kinda hilarious and I would love to see it happen. It would be interesting to see how long it would take to break even in gem value compared to just buying a typical gem bundle of an equal price.
Its better than paying for cosmetic pets at least 
I can’t believe there’s a thread literally asking for something to be pay walled. 
Sorry mate but this was a big ask and we all know this wouldn’t happen otherwise.
I don’t mind as is the only purchases worth making really are the DK armor and campaign passes, having a paid pet that is worth having would be a fair way for them to make money instead of trying to sell stuff nobody is happy to buy.
I suppose they could just give the Steam/ Android/ Xbox… pet a boost this way