Your Sensibility My Destiny Episode 20

After Ling Yan’s death, a grieving Lin Chi is kidnapped by Ji Ding Yue, knowing she is Mo Qing Chen's weakness. The Emperor tests his three sons using the salt trafficking issue, and Mo Qing Chen gives the best solution. According to the imperial edict, he will be chosen as the crown prince during the ancestral ceremony. Upset, Ji Ding Yue poisons Lin Chi and withholds the antidote until Mo Qing Chen announces he’s a demon in the prophecy at the Ancestral Ceremony. (Source: frankly at MyDramaList)