マジで⁉︎本当に⁉︎(驚き)って英語でなんて言うの？

By adding the "wow" to the "really" will help that person understand that you are surprised but that you don't doubt what they say. I hope that this helps :)

"Surely not?" is a sarcastic but not rude way of expressing your surprise at their talent. It is an alternative to saying "Really?" or "Are you serious?".

If someone tells you about their special talent and you are very surprised. and want to say something like "Are you serious?!" "Really?!" in a surprised way. (not really doubting the person, but just surprised), then one of the above example sentences may be appropriate.

If someone tells you something and it has surprised you then all of the terms would be fine as an informal way of saying that it has shocked/surprised you

These are common expressions that native speakers use when they hear information that is surprising, upsetting, or unexpected. Remember that 'kidding' and 'joking' mean the exact same thing. These phrases are informal, but they can be used for formal and casual conversations. Examples: "You're a professional dancer? You've got to be kidding!" "You play the drums? You must be joking because I also play the drums!"

You could say it like this: "You can't be serious right now!?" There are some other names to it, but this one will suffice as it's the most used one. Here's how to use it in sentences: A: I'm having a baby in December! B: What?! You can't be serious right now!?

In order to vocalise that you are surprised at a persons unexpected talent, you could say something very simple such as "Wow" or "Really?". These one word replies signify that you are very shocked but at the same time you are really impressed as you would not of expected that from what you know about them. You could also say, "You've got to be kidding". This is a very informal way of showing your surprise.