What is the fine-grained topic of the following text: The colorful celebration is a period of both abstinence and fasting, and is observed as a day of thanksgiving and paying penance in commemoration of the day when the Hindu Goddess Pavarthi gave her son Lord Muruga -- the god of war and fertility -- an invincible lance with which he destroyed evil demons. Only return the topic.
Hindu celebration commemorating Goddess Pavarthi giving Lord Muruga an invincible lance