Cheng Xiao had overestimated his strength or perhaps underestimated the power of the Shadow Fiend. Even with his Southern Dipper Waterfowl Fist, he was unable to kill the Shadow Fiend, who could continuously launch grenade-like fireballs. Moreover, not only was he unable to defeat the enemy, but he was also in danger himself.
(In fact, escaping would be easy with the Green Goblin Glider's propulsion system, which could outpace the giant bat in seconds. But if I do that... they are doomed.)
Cheng Xiao's gaze shifts to the ground, where the protagonist Eragon, and others are desperately trying to escape the encircling flames. The Shadow Fiend, Desa, is constantly watching them, ready to throw fireballs to trap them again if they try to flee beyond a certain range. If Cheng Xiao run away now, those three humans and the dragon will surely die.
