If you shoot the deer with the rifle and mention the name of Allah, and hit the deer, and it dies from that shot, then it is lawful and it is permissible to eat it. If you catch up with it when it is still alive, it is essential that you slaughter it properly.

No wise person would doubt that drugs are haram, because of the textual evidence that points to their prohibition, and because of the extensive harm that they cause.

Alcohol is haram because it is intoxicating and contains a substance that makes people lose their minds. Allah has forbidden everything that harms the body and mind. For more, see the detailed answer.

The vermin of the earth such as snakes, scorpions, dung beetles, cockroaches, rats etc., are haram. This is the view of Abu Hanifah, Ahmad and Dawud (may Allah have mercy on them).

There is no evidence to suggest that it is haram to eat duck or pigeons, so we go back to the original principle, which is that they are permissible.