It was used by Hiruko or whatever his/her name in some fillers. I know it absorbs chakra and then you can release it back. I think it can absorb wind, lighting and fire, not sure about water.
Hiruko was a movie villain and he stole it from a Kirigakure shinobi using his Chimera Ant technique. Because it absorbs chakra, it can absorb virtually any energy element, but this does not mean it cannot absorb solids. Lower ranked earth/water techniques can be absorbed just fine. Anyway, give this a read.
The method I've used in order to make a better understanding of Dark will make things less confusing for you, at least I hope so. Dark Release is divided into two categories, that of "Absorption" based Dark and "Release" based dark. Now the former deals in absorbing chakra (mostly energy based elements, however higher ranked Dark techniques can even absorb Water or Earth at some point). The dark marks located in your palm need to be short range away from an attack for them to absorb it most of the time. Whereas the Released version of Dark is releasing the absorbed chakra in the form of raw energy, which is alike to light blue flames. This form of Dark does not have the ability to absorb things. Normally, a hit from this raw energy grants death to almost anyone. A B-rank dark explosion is enough to deal life-threatening damage. Another branch of the Released version is that beside the blue flames, it can also come in blast and shockwave version; things which will be portrayed to you during the training.
Because Dark marks are the entrance to another space/time dimension, they can store up an infinite amount of chakra. Because of this, the chakra we absorb does not affect our bodies. So, that said, let me ask.
Can Dark Release absorb Sage Chakra? No, or yes, provide me the reasons.