This is just a redefinition of the PERS so that when a 
immortal is invis and uses a channel it will say 
Immortal instead of someone.

In Merc.h find this line #define PERS then remove the lines there and replace them with this



#define PERS(ch, looker) ( can_see( looker,(ch) )?             \
			 ( IS_NPC(ch) ? (ch)->short_descr        \
			 : (ch)->name ) : IS_IMMORTAL(ch) ?      \
			 "An Immortal" :         \
			 "someone")   

Just do a clean make and it will work