Forgotten Tales

When I get near the Mall of the new map, I spot a small island below how do I get there? Or this map is not released?

Are you talking about the map in the bottom left corner?

The way to get to that island is through the teleporter maze. Its entrance is one map right, where all the ghost archers are.

Be warned - the enemies through there are very tough, and I think there's a level restriction on the tower there.