The Destructo Ray, also known as the Ray Gun, is a collectible Relic, only capable of deleting blocks. Both triggers delete blocks, and it has twice the range of all other Build Tools.
Using the Destructo Ray quickly as a client will make the gun lock up, and it will not fire for a short period of time. This was implemented as an anti-griefing measure, and does not happen to the host of a game.
The Destructo Ray relic was brought into the game once released in April 8th, 2011.