8th denotes secrecy and bad debts hence planets in the 8th from lagna and 8th from arudha lagna has to be seen for health and bad debts

Karakamsa is the placement of the AK in any sign of Navamsa and the sign in which AK is placed is treated as lagna hence Karakamsa lagna

Badhaka is that which cannot be identified specially when nodes are involved. Various remedies are prescribed for removing badha