For Demons who practiced the strategy of utilizing elite forces, Spellcasters were one of their most important assets. When facing a Demon Legion vastly outnumbering them, the Demons relied on strict military discipline, dense formations, and efficient polearms to deal with Prime Demons and Coward Devils acting as cannon fodder. However, Middle Rank Demons were not so easy to handle, and Middle Rank Demon officers were also reluctant to put themselves in danger lightly.
Therefore, the Demon armies were quite reliant on those Spellcasters loyal to the Nine Hells, using them to deal with targets that posed a greater threat to ordinary soldiers. And what Lancelot was doing was knocking out these 'high-value assets' one by one.
