Metal: Hellsinger (Xbox One)

[This isn't accumulative]
When you eliminate at least 1 enemy you will see a combo on the right side.
Eliminate 10 people [while the combo is still active].
The achievement will then pop!
Easy!

Hit streaks are combos for hitting a perfect or ok hit on an enemy while not getting shot inbetween. Make sure you calibrate your sound and video so you dont hit offbeat which will reset the counter.
Using the skull (Paz) can proof effective since he doesnt deal alot of damage so you can get more hits in on an individual enemy. Shoot via RT while rhythm indicators are overlaying, the 10 streak is pretty easy and doable in most game levels.