Ummmm to do what?
If you're talking about Auron's "Mars Sigil" then we have already talked about this many times in the forum. The write-up is here:
http://www.bellaonline.com/gaming/strategy_lib_ffxwalk_ua.html There are not 10 monsters in every area! Some areas have more, some have less. The instructions say:
"The Mars sigil is about capturing things. Capture fiends from 10 areas to get it from the arena guy. "
Have you captured the fiends in 10 areas yet?