No, you cannot move via Lightning Rush while prone. You can use Lightning Rush against the enemy adjacent to you as the Move part is an effect. Being unable to do it does not limit your attack in any way.
Effect: Before the attack, you move your speed to a square adjacent to the triggering enemy.
Ok, so before the attack you move, what is Move? Luckily for us it has a specific definition.
Any instance of movement, whether it is done willingly or unwillingly. Whenever a creature, an object, or an effect leaves a square to enter another, it is moving. Shifting, teleporting, and being pushed are all examples of moves.
It's common to confuse Walk with Move, but the two are distinct. Movement encompasses any way that you go from one square to another, while Walk is an action you take which allows you to move.
Movement: Move a number of squares up to your speed.
So is Crawl:
- Prone: You must be prone to crawl.
- Movement: Move up to half your speed.
Alright, so Crawl and Walk are both examples of movement. Seems like Lightning Rush would work as it doesn't specify how you must move from one square to another, right? Unfortunately, the definition of Prone shuts you down.
the only way it can move is by crawling, teleporting or being pushed, pulled or slid.
Prone restricts the ways in which you can move. In the same way that Walk is prohibited, so is Lightning Rush.
By the way, if you were to allow Lightning Rush to work, you're going to make every charger in existence very happy as Charge specifies Move as well, not Walk, or Crawl!
Move: The creature moves up to its speed toward the target.