Lightning that tracks enemies with range in a 2d topdown

I'm (attempting) to make a 2d topdown rpg kinda game (styled after enter the gungeon), but I'm new to unity. I want to give the mage an ability to shock everyone withing range for a limited time, shocking everyone for damage as long as their within the range. If anyone can help me or direct me to a place I could learn something applicable to this, please do! Thanks in advance.