Thunderbird

The second among the Bird-type enemies, this creature can actually become a danger because its physical attack is invoking an small storm by flapping its wings. This might not look as much, but if you're playing in Hard, this could end up wiping out all your party members in one hit if you aren't careful. Try to keep your distance from it and guard while you try to attack. Also, make sure to use any healing items you have at your disposal if your HP drops too much.