Which AI Gen tool would allow me to "compose" a picture with references?

Hello, folks.

My sister, my brother, our friend, and I play online video games together. One of those games is League. For a Christmas present, I would like to compose a picture of our main champions together in a particular way.

So I need an AI gen tool that I could feed pictures of our champs for references and to imitate art style, and then ask it to generate a picture with a particular composition, and possibly to alter it with further prompts for details instead of re-generating again.

Which tool would best fit my purpose?

Thank you in advance.

(This is not for profit, this is for single-use private present)

EDIT: looking into it myself, I am finding some options, but most require setup. Since this is a once-off project, I would rather something that is more straightforward.