The Strongest Sage with the Weakest Crest 16 (manga)

Matthias and his party embark on a quest to hunt down a group of battle-crazed killers from Matty’s past life that have been resurrected by a Devastar. The resurrected killers are eager for a good fight and Matthias gives them exactly what they want. In return, Matty gains critical knowledge about mysterious figures who used the Devastar to intentionally resurrect the killers and Grevil. In order to find these mystery men, Matthias volunteers to be a test subject for their magic experiments!