This is something that is similar to an already existing post, but here, the idea is to implement a finishing move usable on all enemies and not just bosses.
Here is a simple explanation :
Enemies could have a hidden (or visible) stun gauge. When you hit the enemy with any attack, the gauge fills up. Once full, the enemy drop to the ground and stop moving for a while. During this time, if you boost into a stunned enemy, your MASS automatically performs a finisher.
The finisher in question can be anything simple enough. Grabbing the ennemy’s leg and throwing it at other ennemies, kicking it in the air and finishing with a rifle shot, or just a slash through with your melee weapon. The idea is just to add some kind of personnality to the MASS you’re controlling.
You wouldn’t need to press any button to perfom the move. Just boost into the enemy, and the system will automatically picks a random finisher based on the weapons you have equipped. The duration I have in mind for the finisher would be around 2-3 seconds.
The stun gauge could fills slower if you keep using the same attack or the same melee combo. It would recommend players to play with more variety.
The finisher could actually not finish the ennemy (unless they don’t have enough health of course), but would concentrate more on AOE and crowd control.
What about if you only have one weapon ? In that case, the stun gauge could be shorter and easier to fill.
There are many possibilities here.