NIFTY opened like a 300 point gap down two weeks back. Here is how you could have made (or lost) 15k with just 50 k capital in 10 minutes!
Here is Balajee Ramachandran, our front end engineer and an Options Trading enthusiast, with his real life Options Trading Experience
https://www.youtube.com/watch?v=0FLzxdRP3Kw
The moral of this story is that you should always check IVs before you trade. And you can check that quite easily with Option Chain by Sensibull