Thanks for the concern..
After do like you said, the NPC can be use and can summon MVP. But on the map-server, got these debug :
inside function script int__ {
find
set .@num, atoi(getarg(0));
and replace with
set .@num, atoi(""+getarg(0));
coz it happaens when u update mercenary_db by using @reloadmobdb command
but that coommand doesn't reload elemental_skilldb and read mercenary_skilldb
so you must use @reloadskilldb after @reloadmobdb