The Island Heart can be randomly obtained by killing the gorilla boss during the island quest.
2.1. Quest Details
After entering the island, you arrive at the circle near the repair gui. 3 minutes after you entered the island, you may climb up the vines into the first explorable area marked by the green circle below in the image.
Once you climb up, a random path from the first green circle will open up. The paths you are able to take are random. Before entering another green circle, vines will grow and gorillas will spawn which you must kill before proceeding.
The boss spawns are random and paths are random too.
