I feel like if there were going to be new specialist packs in the future which can be purchased, or just some extra specialists, this class of specialists would certainly be interesting. I'm not saying you should be able to pay for these in game as like a one time purchase, because that would make the game 'pay to win'. You'd have to buy the pack, and if you choose to use it upon a game creation, only other people with that specialist pack can join the game.
The idea is that upon hiring this specialist you then have the ability to have it do something to you or your enemy that works for a period of time. Then the specialist is useless unless you have a general. (or maybe the specialist just disappears?)
Here are some examples. Of course, all of them would have names, but I'll leave them to others to name them.
1. +30 max shields for 18 hours. Recharges all of them right after hire. (So you would be able to choose when you would want the period of 18 hours to start, and same with the others)
2. Provides 'double the effects of funding' for 18 hours.
3. Immobilizes all enemy subs that are not gifts coming towards your outposts for 16 hours. (enemy's lose control so navigators can't change course either)
4. Doubles the speed of your subs for 12 hours.
5. Doubles the effect of all your specialists where applicable for 4 hours.
6. You have a limitless driller cap for 24 hours.
7. Triples the number of drillers produced at each of your factories at the next production cycle.
8. Upon being captured or taken control of by an enemy, halves the speed of all their subs for 12 hours.
9. Upon being captured or taken control of by an enemy, destroys 50% of all drillers on subs that are not already gifts.
10. Upon being captured or taken control of by an enemy, halves driller production speed for the next 16 hours.
11. Upon being captured or taken control of by an enemy, renders all their specialists abilities useless for 4 hours.
12. Upon being captured or taken control of by an enemy, disallows them to send any new subs for the next 8 hours.
13. Upon being captured or taken control of by an enemy, renders their shields useless for 12 hours.
the 'Upon being captured or taken control of by an enemy, 'phrase' could potentially give more value to saboteurs and (maybe?) assassins. It could also bear the possibility of an enemy giving an outpost away to the speciliast because they didn't want the effects to work on them at that time.
Stacking would also be interesting, and would seem slightly OP to start with, but remember that they are only temporary effects and they cost 1 specialist hire, so I don't think they would be all that OP. They would provide people in losing situations to have a chance of revival, or people being attacked to defend better, or you attacks to be stronger, etc.
These are just some ideas. Any suggestions, feedback, ideas, or anything else is appreciated!!