The Ender Medallion is crafted with 4 clay bricks and 4 gold nuggets and a ender pearl in the middle.
The medallion is charged via staring at endermen, when fully charged it turns into an Area of effect weapon (splash).
Also, when crafted with a knife or sword, it adds an ender augment. To use it you need to charge the weapon then aim at an enemy. Once released you will teleport to them, attack, then teleport back to your original position.