[Septimius Severus]

I disagree with Ano about the possible utility of the merc, but it will remain to be seen how it functions in actual play (I would keep retention of services private and only list the menu of what is offered). Take something as simple as province information or scounting. There are times you may need fast/cheap/complete information on a given province that is located some distance from you. If pluncking down 5 or 10 gold can get you the information you need to make your decision without wasting gems (if you happen to have Astral access) it may be worth it.

The benefit of using the merc, is it enables your team to do things without taking risk/wasting gems/using your own troops/etc. For instance, you could be allied with team B but attack team B at the same time without team B knowing who ordered the attack. Why use risk your own troops against the AI or an enemy in some province when the merc can clear out the province for ya.