You don’t directly spawn things from the animation blueprint, it needs to be done in the Character (or PlayerController, perhaps.)
If I remember correctly, you’d create an Event Dispatcher in the Animation Blueprint, call it something like “spawn fireball,” and then in Begin Play, you bind the event dispatcher from the blueprint into some event that actually does what you need in the Character.
To do that, you’ll need to get the animation instance of the character mesh, and cast it to your blueprint class, so you can find the event dispatcher. Again, if I remember correctly – I made a thing like that a few years ago, but I forget the exact details.
… I dug up an example in the Amplify Animation Pack, and added an event dispatcher to it, so, yes, it seems I remember right:
