so i found this idea and i think its golden
Say you want to take on the face of an NPC to help with a quest, gather some information or just go incognito in an area. Rather than just taking just the appearance, you can take on the entire profile by kidnapping or taking out of the picture said NPC so you can take his/her place. You can do the same with one of your companions, just get that person imprisoned and do something heinous to get a bounty on your head and then watch what happens next.
You also have to learn a bit about your target or they'll catch onto you.
Allow shapeshifting of certain notable figures, introducing various elements like:
-Target research: dialogue with NPC and journal entries allow you to investigate your target and plan ways to kidnap, incapacitate or just flat out take out of the picture.
-Suspicion level: Associates of the target will be suspicious if you act opposite to the way the target normally behaves and your cover is blown if it escalates too high or you fail an important checkpoint. Makes it more necessary to carry out planning before shapeshifting.
-Poor planning consequences: Your target can escape and mess with your plan or someone will find his/her dead body if you didn't dispose of it properly (maybe his ghost will just mess with you).
-Combine with quests to create alternate ways to complete them- such as using a kidnapped politician's appearance to investigate a corrupt military unit or assassinate an important target stealthily by going to bed with him- going the femme fatale route.
Consequences of overusing shapeshifting-
For example, getting caught while shapeshifted will trigger a bounty on your head and lower your reputation by a significant amount.
Your combat skills will be limited because an old mayor can't use source magic and shatter the heavens with lightning bolts. To make it fun, all your abilities are usable at any point but if you use an ability that your enemy can't- your disguise is blown- here research again becomes important.
Appearances can't be reused without doing the kidnapping mechanic again. Makes you resist the temptation to just assassinate everyone because you never know when me might be useful again.
Your target's ghost can haunt you while you're shapeshifting if you killed him/her and didn't absorb his essence.