Cleave is most often used as a skill name
The arpg terminology you are looking for is Splash damage
Ofc it should become part of D2, greatly reducing the gap between melee and casters
But it has to be done a in way that isn’t mandatory… it has to have a drawback so you can make the decision to use it or not
Imho the best way to add melee splash to the game is by linking it to Knockback
A melee mechanic that is considered garbage and counter productive and rightfully so
But by adding splash to knowback you justify using Knockback on attack builds and you create a drawback not making it a must have absolutely
It also makes total sense that if a monster is knocked back, it collided with other monsters transmitting his kinetic energy to them resulting in damage
With the monster size you can modulate the size of the splash
Bigger = shorter but larger
Smaller= longer but narrower
Bosses= Extra damage since they can’t move