The phrase "lay waste" typically refers to destroying or ravaging something. There are several synonyms that can be used to convey similar meanings, such as decimate, devastate, ruin, annihilate, and obliterate. These words all suggest a significant level of destruction or damage being inflicted upon the subject in question. Other synonyms could include wreck, demolish, and flatten.
The choice of synonym may vary depending on the context in which the word is being used. For instance, decimate may suggest a large portion being destroyed, whereas obliterate implies total destruction. Regardless of the synonym, the idea of laying waste is always associated with significant damage or destruction.