Eldritch Bomb (5e Class Feature)
From D&D Wiki
When you cast eldritch blast, you can choose to form an explosive sphere instead of a beam. When you cast the cantip in this way, the blast flashes from your finger to a point in range that you can see. At that point, it takes the form of a 20-foot spherical explosion of force. Creatures in this sphere must make a Dexterity saving throw, taking 1d10 force damage for each beam of eldritch blast that you are able to cast on a success and half as much on a failure.