The Ambikaa rules this day, which is suitable for killing enemies, acts of destruction, and violence. Inauspicious for ceremonies and journeys.
Shukla Navami is the name for the 9th Tithi (lunar day). It's the 9th Tithi of Shuklapaksha. 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 and Poorva Kalamrita), who's is caring and combining all powers (which are represented as 10 weapons in her arms) for bringing any situations into piece and harmony. As per Brihat Samhita, Shukla Navami is ruled by Nagas (Sarpas) and all actions done in respect of Sarpa deity is acceptable. Regarding Poorva Kalamrita classical text, Shukla Navami is ruled by Ashtavasu.