For minions, neither. Necroclock doesn't really make self functioning beings. It's more like a xenoalchemist, able to improve other party members and/or itself. Mind it also would have the ability to make non-graft devices, but these would be things like, horseless carriages, lights, tools, etc. As for in combat uses and utilities, they would mainly be useful through necroclock devices made for themselves and others ahead of time, but would also have the ability to deal positive and negative energy damage. They also would have the ability to perform improved tuning an maintenance on necroclock devices, allowing benefits to last longer and require less time to complete.
Owrtho