As I recently posted a comment here saying that AMS should only grant RP when taking magic damage (which I thought was the case) I feel this is probably pertinent information. While AMS only absorbs magic damage, it will actually give you RP from any damage taken. This screenshot is an example:
This discovery (new information, at least to me) won’t make any significant difference to DPS DKs. You can now AMS through XT’s Tympanic Tantrums to gain RP, though you’ll be wasting the cooldown in case you get light/gravity bombed. There are other situations where you take physical damage, such as from adds in Thorim’s arena or the Freya encounter, when there are simply too many for tanks to pick up and hold immediately. If you notice you’re getting hit, and don’t think you will need to absorb any incoming magic damage, by all means pop AMS and get some free RP.
For tanking, you now have another avenue for getting lots of RP quickly. The downside is that as a tank, you often want to have AMS up to protect you from the crazy amounts of magic damage that bosses put out. So I would keep in mind that AMS can energize you from any type of damage, but always think before you use it so you don’t become vulnerable and make your healers work extra hard.
edit: This appears to have been fixed and no longer works.