The Ambikaa rules this day, which is suitable for killing enemies, acts of destruction, and violence. Inauspicious for ceremonies and journeys.
Krishna Navami is the name for the 24th Tithi (lunar day). It's the 9th Tithi of Krishnapaksha. It's nature is Ugra Prada, which can be interpreted as "increase of aggression". It's good for following works: hunting, poisoning, making of fire arms, fire, gambling; drinking, making alcohol drinks; quarrels, opposition / encounter. Durga is Devata which rules Navami (referring to Muhurta Chintamani), who's is caring and combining all powers (which are represented as 10 weapons in her arms) for bringing into situations into piece and harmony. As per Brihat Samhita, Krishna Navami is ruled by Nagas (Sarpas) and all actions done in respect of Sarpa deity is acceptable. Regarding Poorva Kalamrita classical text, Krishna Navami is ruled by Ashtavasu.