Final animal king

Like others I'm stuck with only 3 letters and missing 2 quests, one of which I think is the final animal king. It seems like he is a . I've seen something about the attracting him, but have walked all over
. Is there a specific area he triggers? Also is this another random trigger? Or do I need to find a hidden cave opening somewhere. Thanks! 
Spoiler: show
Spoiler: show
Spoiler: show

