The Eminence in Shadow, Vol. 4 (manga)

Cid is invited to Lindwurm, the Sacred Land, where a ritual known as the Goddess's Trial is held. Ancient warriors are summoned according to the strength of the challenger, providing an opportunity for honor and glory—all the normie stuff Cid specifically wants to avoid! If his truestrength is revealed, all his work to play the part of anobody will be for naught...

Volume 4 of The Eminence in Shadow manga series by Anri Sakano.