"The White Rider. Liberate 30 slaves in 180 seconds while riding a caragor."

Looking at this achievement it may seem difficult (at least I thought so, but I hate time based achievements), but when I tried getting it it was really easy, so this is how I did.

Things that will help while getting this achievement is a talent point in Quick draw, so you can use focus and headshot the orcs that are in charge of the slaves, and these runes really made it easier

Step 1. Find a caragor.
I went to a stronghold since they have a lot of caragors in cages there, and you can stand on the ramparts to mount them from above.

Step 2. Blitz from stronghold to stronghold.
It is very easy to find slaves this way. (Though to be honest I have not tried any other way, so they may be equally valid.

Step 3. Once you find the slaves.
I took out my bow and headshotted the slave handlers.
Rinse and repeat until you've liberated 30 slaves.

Hope this guide helped someone :)