During his research on Jūgo's clan, Orochimaru eventually tracked down the source of their power when he discovered the Ryūchi Cave and senjutsu. Here, he attempted to learn senjutsu as well as Sage Mode. However he was unable to use this power to its full potential due to being unable to find a host body that could bear such an ability, making it an unsuitable option for battle altogether. However he does have enough knowledge to both release another person's Sage Mode and absorb the senjutsu chakra inside them as seen with Kabuto. 

 

  To compensate for this flaw, Orochimaru developed other novel uses for his senjutsu chakra: thecursed seals. Combining this chakra with the enzyme produced by Jūgo, he was able to create these unique seals, which triggered a change near-identical to that of the Sage Transformation, but with different benefits and drawbacks. The senjutsu chakra locked in these seals is naturally quite powerful as Kabuto was amazed at a portion of Orochimaru's chakra he absorbed from Anko, even after he assimilated the collective DNA of team Taka, the Sound Five and of Orochimaru himself. These seals also carried the additional benefit of acting as anchors to Orochimaru's consciousness, allowing him to observe events through anyone branded by the seal and even revive him any number of times under the right circumstances.