Look at the artist's tag. If it says;
Then please DO NOT use their work in an edit.
It's also really bad form — and against our rules — to not give credit to the artists whose work you use in edits.
In the future, if you use someone else's work in your edits, please make sure before using their art that they are ok with their work being used in edits (ie: get permission) and please make sure that you both tag the artists whose work you use in your edits, and tag the upload as an "Edit".
As to a list of artists who welcome edits, there are some, you could do a search for "trace" — if an artist has allowed a trace of their art to remain on the site there's a better chance they are ok with edits of their work.
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