1. Hello everyone, does anyone have an idea how to make something like this: Lets say when someone casts flash light on me I want to cast fan of knives ( just an example ). I guess it would be UNIT_SPELLCAST_SUCCEEDED but I got no idea how to write it. Would be great if anyone could write me a simple addon. Thanks in advance.

    You cannot cast a spell in response to another spell. The best you can do is make some notification that says you SHOULD cast the 'other spell' but nothing can make you cast it.

    Is there any way you could write me a brief code how to make it so it notifies me about? Thanks.

    I would recommend to take a look at Combat_Log_Event_Unfiltered - there you'll find all what you need: