Inquisitor 1852

[Gojira]

I have come grinding halt. Have filled grid, identified and changed the four unclued entries and have a name from the asterisked letters, but that is where I have stopped. I can't find any artwork from the letters of the extra 21 words, nor any four word depiction that could help identify the artwork. Any help to complete this would be much appreciated.

[qesue]

If you google the artwork title you will get a picture which helps

[ProfessorMaisie]

Anagrams of the extra words give the title in clue order (from the initial letters of the new words).

The description isn't a phrase - the illustration has 4 parts in the foreground (3 of them forming the central object).

For the final 4 highlighted cells, 'compound' is the key word in the preamble (they're in the appropriate place higher up).

[Gojira]

Many thanks for help. Moving forward now.