I have top level earth killer and it's most universal character you can have:
Decent damage with enough str.
Earth def bonus.
Stone wall skill.
JS does double damage to sealed enemies.
DS has 27% chance to terraficate your non-wind enemies for 4 turns.
FS blocks 75% of damage for 4 or 5 turns.
Generally, earth killer is very tough fighter that is able to keep whole party alive.
Recommended pets: Con-built Elin, Kanako or Xaolan as primary pet.