What is the ruling on a wet dream during a supererogatory fast, and does it invalidate it? And what is the ruling on intentionally smoking or ejaculating, and does that entail making up the fast or offering expiation?

A wet dream does not affect the validity of the fast, whether it is an obligatory or a supererogatory fast. As for intentionally breaking a supererogatory fast by smoking, masturbating, or other means, it invalidates the fast, and there is no expiation (qada') required for it, due to the Prophet's (peace be upon him) saying: "A person observing a supererogatory fast is his own master; if he wishes, he fasts, and if he wishes, he breaks his fast." Some scholars have recommended making up for it (qada') to avoid disagreement. It is important to note the prohibition of smoking and masturbation.