Something you made wrong. If you ara receiving "Unknow command" its cause you don't add this line right "BUILDIN_DEF(fakeplayer,"siisiiiiiiiiiii")".
@monsterGID = fakeplayer( "prontera", 150, 150, "blabla", 0, 0, 1, 2, 0, 0, 1, 2, 3, 0, ! );
Try to put the modify in script.cpp so.
There is no "right" place to put it, but ok:
You can put it before this line:
static int buildin_addrid_sub(struct block_list *bl,va_list ap)
and the build_def:
Before BUILDIN_DEF(mes, "s*")
Like the title say, this is a script commands.... not a atcommand
prontera,150,150,5 Script FakePlayer 90,{
.@monster_gid = fakeplayer( "prontera", 152, 152, "blabla", 0, 0, 1, 2, 0, 0, 1, 2, 3, 0, 1 );
mes "Congrats, I summoned the monster with id " + .@monster_gid;
close;
}