Bismihi ta'ala

At the end of times, prior to Qiyamah, there will be Raj'ah; the return of the purest and the return of the wickedest. 

This is when retribution will happen, and those responsible for the worst of oppression will be held accountable for what they did. 

This means that in Heaven there will be no more sorrow or grief or sadness. Indeed, as our ahadith say, attending the Majalis of Imam Husain (a.s.), weeping for him and the tragedy of Karbala, writing poem for him, and everything related to serving Imam Husain (a.s.) will amount to mandatory entering of Heaven. 

This itself is the greatest blessing, if we do it sincerely and with correct ma'rifah, truly recognising the status of the Imam and following his teachings in practice.

If we are fortunate enough, we could also be in the vicinity of Imam Husain (a.s.) and Ahlul Bayt (a.s.) in Heaven, in shaa Allah.

And Allah knows best.