How can I code a mob that acts like the Wither Storm?

A very intensive way to do this would be on entity tick to make blocks around the mob falling blocks, then for each entity around the mob that is a falling block, override its velocity/movement to be closer to the mob, with some random variants. However this method could cause lots of lag if there are more of this mob in the world, a way to reduce the lag would be to have the convert blocks into falling blocks, only happen as like a 1% chance, but keep pulling the falling blocks in on every tick or 50% chance every tick.