Exdeath is lurking around the Mosphoran Highwaste, but again there's some
stuff you have to do first in order to get to him. In the camp area
in the Mosphoran Highwaste, find the South Wind Shrine (南々風の祠)
and activate it to cause the little platforms to rise into the air. Go
northeast to the Ashen Roof (灰色のひさし) and you'll find a Chocobo
wandering around. Feed him a Gysahl Green (ギザールの野菜) and then
go south to the Road To The Sky (天空へ続く路) zone. On the western
part of it, after crossing the platform you previously raised, you should
find a Chocobo-only path. Go through a couple of zones and you'll be
back in the camp, only in an area on the western side that you couldn't
access before. Activate the West Wind Shrine (西々風の祠). Go
north from here and you'll find that you can shove the rock out of the
way to connect this little area to the rest of the camp. Activate the
Northwest Wind Shrine as well now (西北風の祠). Now with all
that done, you can go to the Ridge to the Sky zone (空の果てを知る尾根)
and climb all the way up to the plateau in the middle, where Exdeath
appears.