Haven't had much time to play, but I ran into my first mammoth yesterday. I think I was around lvl 7 at the time (2H Orc warrior type).

Never knew the damn things could move so quick. I hit it with a couple of arrows from afar and then was very surprised at how quickly it was able to run at me crush me. There were two hits. It hitting me...and me hitting "re-load".

It was epically fun. Now...if I can just find a way to give Snuffleupagus some payback, all will be right with the world!

Easy kill to mammoth > a medium sized rock to walk around.

But, I thought you had tiger blood and Adonis DNA? Seriously though, I got my ass handed to me the first time I took on a mammoth too. You especially don't want to mess with the Giants!

On my first encounter yesterday I found they can get stuck fairly easily on terrain. Problem was my ranged attacks weren't doing anything, and when I tried to get in close after a long chase he and his giant buddy slaughter me D:

I keep finding that everyone says a small rock can confuse these mammoths, but I've had mammoths climb straight up mountains and over trees to kill me

Mammoths are mean! they make great big targets though... I ran into them a few times and finally decided it was time to hunt them, I shot at it from a fort as it was too big to get inside the front gate hah... but his giant guardian wasn't, slipped right in and weeee I went flying!!

you can find an area where there's a low bridge and it will get stuck. Use terrain for the big nasty enemies. I even use terrain when fighting dragons, frost trolls, etc.

I've seen this for myself with the small rock thing. They take the long way to you.

Sprinting is your best friend. I was able to take on a giant and two mammoths at the same time on my archer by fleeing a large distance, launching a few arrows, sheathing my bow, and fleeing some more. It took me forever, but I eventually killed them all with upwards of 30 arrows.

You need to keep mobile, and try to stop the mammoths from chasing you with Unrelenting Force. It stops them in their tracks for a few moments, enough to get some distance.

Not climbing trees, but I've seen them climbing mountain to kill me too :/