Agad Tantra is the branch of Ayurveda, which deals with bites of poisonous animals such as snakes, insects, spiders, rats, etc and their treatment and symptoms of different poisons, their combinations and their treatment.

अगदतंत्र नाम सर्पकीटलुतामुषकादिदष्टविषव्यांजानार्थ विविधविष
संयोगोपशमानार्थच // (सु सू १/६ )

Gada means the disease, pain, or visha (poison).The word Agad
means by which the disease, pain or poison (Gada) vanishes.The
Science of medicine, health, or science of visha chikitsa is called as Agadtantra.

The brach Agadtantra gives complete knowledge about visha and upavisha (i.e a variety of toxic and poisonous substances obtained from plants, animals, minerals, metals, etc) , their adhisthana,their sources i.e. utpatti of visha, vishayoni,their characteristics and properties i.e. visha gunas, the symptoms which is produced by their consumption i.e. visha lingani, the lethal dose i.e.ghatakmatra, the nature of fatal results i.e. visha vega, signs and symptoms produced in series one after another). It also gives the knowledge about their antidotes and the Upakramas which are used to combat the action or effect of Visha and the method of their detection and estimation i.e. vishapariksha.

Definition of Visha-

The word Visha is made with two words i.e Visha-Ka means which spreads in the body rapidly.

Visha’ is a substance, when entries into the body cause the disturbance of all the functioning of rasas, doshas, dhatus. and malas, and responsible for vitiation of all doshas,dhatu and malas which results in not only the degradation of the health of a human being but sometimes leading to a destruction of life also.

According to Charakacharya, the substance which creates sorrowfulness (vishada) in the mind of the affected human being is called as VIsha

Acharya Sharangadhara says that-Visha is a substance with Agnimahabhoota pradhan and it is the destroyer of life and yogavahi in nature(synergistic in action)

Visha Gunas-

Visha contains 10 gunas which are totally opposite of Ojas gunas.

1.Laghu
2.Ruksha
3.Ashu
4.Vishada
5.Vyavaye
6.Tikshna
7.Vikasi
8.Sukshma
9.Ushna
10.Anirdeshya rasa
11.Apaki (some are explained this guna instead of anirdeshya rasa)