Background[]
The Siphon seal works as its name suggests - it's innate ability to mark a target with the sigil of the Siphon Seal will cause a rapid drain of exposed chakra, meaning any chakra modes will be drained rapidly and will significantly increase the cost of said chakra modes.
When the Siphon seal has been marked and placed on the target - a follow up marking is placed on the users palm that shows a direct channel of chakra from the Siphoned marked seal and the one now present on the user, the user doesn't gain any of the chakra taken but it is instead stored into the seal, if the chakra taken is of superior quality (Bijuu) it can be used to boost the users ninjutsu for a one time attack.
Weaknesses[]
The Marking is easy to overload by surging more chakra than it can drain will break the seal and return ALL taken chakra.
The Seal the user gains during this Siphon will remain on the users palm till all chakra is expunged from the seal - meaning all other benefits from seals on the users body is suspended.
The Seals chakra capacity is of that of a Clanless Chuunin's chakra reserves. (30/100 for example)
The user can't directly use the chakra siphoned and add into their own pool
Trivia
- Sumiko Uzumaki uses this seal to subdue strong patients during operations to prevent them from unintentionally attacking her staff.