I got a call from IIM Rohtak with 84.21 in the CAT NC OBC. Should I go for it?

It would be much clearer, had you mentioned your background. However, assuming two separate perspectives, let’s divide your present scenario. The first one is your work experience, while the second is your level of seriousness while preparing to give an attempt at CAT.

1. In case your work experience is slightly less than 2 years, but you still went for a serious attempt: It might be a calculated risk. If you are confident enough about leveraging your present work experience, then you should secure at least around 95 percentile in the following CAT exam since it will help you become eligible for older IIMs.
2. In case your work experience is supposedly less than 2 years, and CAT is a casual attempt: You might want to appear for the exam since you can still afford to lose one year and will be able to reap maximum benefits of your work experience once you get selected to an IIM.
3. In case your work experience is more than 2 years, but the CAT exam is still a serious attempt: Unfortunately, it might become highly risky, given your present scenario. CAT is sometimes extremely uncertain when providing scores. So, it will be safe to go for it.
4. In case your work experience is beyond 2 years, but it is a casual attempt: Similarly, the risks here are quite the reflection of the former statement. However, if you still have a really good job, and you personally want to add value to your profile nonetheless, then you can stick to it and try again another year.

IIM Rohtak is undeniably a reputed and well-known B-school and will secure you opportunities that are as similar as what other newer IIMs provide. The best way you would be able to leverage your quota will be your high scores, which should at least range somewhere around the 95 percentile. It will help secure a position at older IIMs. you should always analyze your chances, the recent market exposure your opportunities have. Depending on these issues, you should finally decide what you should go for.