In his earthly pastimes, whoever gets killed by him, they attain the Moksha (liberation) from the bondage of birth and death and attain the spiritual eternal abode of Lord Krishna permanently. read more
He requested both Lord Krishna and Arjuna to help him consume Khandava forest which was known for its herbs and they did. So, Krishna didn't massacre the forest, he just helped or rather guided Arjun to build an arrow-roof so that Agni can consume the forest and cure himself. read more
Arjuna and Krishna armed themselves and went near the edge of the Khandava forest. Krishna nodded to Agni. Agni then turned to his natural form. A small fire started in the forest of the Khandava. read more