Unrelenting force might as well be one of the deadliest shouts, since it sends most enemies (including Giants),
flying quite a distance.
Aiming it so that your opponent gets launched off a cliff, wall, bridge or what ever you can
think of is a very effective way to kill.
Always try to pay attention to and use your environment in tough battles.
I killed 4 frost trolls with one shout when I was mining gold on a mountain southwest of windhelm.
Yes, there is a cave up there, right next to the gold.
Acting like guards they are just sitting there waiting for someone to try and take the gold.
By running past them, turning around, Moving quickly until I have the high ground and the trolls were lined up just beneath and in front of me.
With the right timing I could shout them all at the same time sending them bouncing down the mountain to an instant death.
One fus ro dah, 4 dead frost trolls.
While attacking a fort, while doing the stormcloak or imperial quest line.
You will have many opportunities to shout several soldiers off the forts surrounding walls.
By making as many as possible chase you until they are in position with their backs on the edge of the wall.
I've always wondered what it would look like from the outside as
A spectator lol, seeing dovakiin enter and 1 minute later you can hear fus RO DAH! And then seeing 5 - 6 men flying out of the place, must look quite funny.