Has anyone found a tool to download whole comics? I know there's a download button on the images but is there a way to download a entire comic pool? Thanks in advance!

There is probably a browser extension for that

Try checking one of these forums
https://e621.net/forum/search?query=Pool+downloader

Or any downloader, and add "pool:123" in the tags, with the id of the pool you want to download.

There's a few download tools here:
https://e621.net/wiki/show/e621:tools