Upon landing a hit with Eldritch Blast, you can cast this spell. Your blast explodes out in every direction from your target, causing massive damage. The radius of damage is equal to the unused range of your Eldritch Blast. Ex. Target 40 feet away, Eldritch Blast's range is 120 feet, the radius of the explosion is 80 feet. Any creature in the outer 20 feet may make a Dex save against your spell save DC + 3. Only one target can be chosen for all four beams of the attack. The damage of the attack is increased by 1 for every 5 feet of radius.

If you have any comments about balancing, please say them so I could make appropriate changes to the spell.