Master Heo: the blood parasite cannot be removed
Heo Yeom explains the parasite sits in Yul's core of energy and only leaves when he dies; his friends refuse to accept it.

Every Alchemy of Souls moment featuring Heo Yeom, in story order. Played by Lee Do-gyeong.
37 moments · 1h 16m · by Favseen
Moments 31–37 of 37
Heo Yeom explains the parasite sits in Yul's core of energy and only leaves when he dies; his friends refuse to accept it.
Heo Yeom lays out a water wick, Yul's energy and the fire bird's power, and explains why Cho-yeon's blood is the key.
A warning about pregnancy sends Dang-gu into a panic; Bu-yeon volunteers and flatly insists there is no chance for her and Uk.
The plan needs a fortune in gold; Uk reveals he dumped his soul-shifter bounties at Jeongjingak and never spent them.
Heo Yeom draws Yul's last energy into the wick and places it in Bu-yeon's mouth; she must not open it before time runs out.
Uk and Go Won use the gold's energy at the fire bird's barrier to pull the parasite from Bu-yeon, then race back to revive Yul.
Master Heo plots to make his granddaughter queen; gossip says the new King practices chastity, and the King recalls a turtle son.