corporate politics

Hello sir I'm working in mnc in Chennai and there s over politics and many illegal things which is happening recently I saw my manager asked one person to buy drinks (alcohol) to gift someone and this was done by my team met which he is close and same caste for my manager As I understood he had done a favour in increament rating etc but even people working like me got a hit badly recently it gone worst and every body things in my team very badly coz of the attitude of my manager and some times its is very visble and nowadays more pressure for me in work area and no incentive according to that if I don also making me as fool since I got mentally harrased and over stresses coz of this since I'm from very middle class my job is important more than that need to work peacefully Kindly help how should I handle legally what proof di I need.thanks