A bit shocked of this entire situation, Eric froze in his spot. It is not that he feared for his own life but quite the opposite. He has never seen Mogranius receiving this much damage ever since he met him! There is an Arrow on his shoulder, his back is burned badly and he is on the ground awake but too weak to move. Perhaps, the screams of pain he tried to suppress just to not sound weak, contributed to this fatigue because it would take a lot of physical and mental effort to do so, without a doubt.
The wounds he saw on Mogranius, were only partial reasons why Eric felt frozen now. It is the fact that such a strong figure dropped down as if he dropped down dead, that got Eric terrified and even to lose a little bit of hope! If seeing Mogranius actually scared wasn't bad and discouraging enough in past events, this situation today tips the clay bottle.