Beastmaster: I Can Choose Hex to Strengthen

Xu Qing traveled to a world where everyone controlled beasts and awakened the Hex Strengthening System. Upgrade: Your pet has no upper limit on level and rank and will gain an additional 20% growth value when upgrading and advancing. Big and powerful: Your pet gains a maximum HP of 500 and its size increases by 30%. Pearlescent Lotus: Your pet's skills can critically hit and gain a 45% critical hit rate. Transformation Reorganizer: Your pet's potential becomes a higher level. … A few years later, Xu Qing was very satisfied when he saw that other people's pet beasts were all at level 99, while his own pet beasts at level 999 had heaven-defying attributes. Who allowed him to choose Hex to strengthen?