Scavenger GuildMaster is smart,, if an experienced S rank died, he'll become MC shadow slave which is extremely dangerous.
but looks like it won't be easy since the bad dude said "We" in the end,, probably other monarchs are with him or he just got one of monarch power.
but our MC won't go down, cuz plot armor never fail and author loves MC.
btw,,
Scavenger GuildMaster probably a monarch too