In the Dune universe, when a laser weapons hits a shield, both are destroyed in a nuclear explosion reaction.
So instead of building nuclear weapons, wouldn’t it be easier to tie a timer and a “parachute” to a laser gun and drop it from orbit onto your enemy’s city?
As far as I know it is random in the sense that the shield-lasgun interaction can either annihilate the target, the laser operator or just culminate in a giant nuclear-like explosion. Therefore you don’t know whether your move will have the intended effect or whether it obliterates only yourself while the enemy is fine. I think this is mentioned early on in the first book.