Free-to-Play Hero Rotation
Raynor
Muradin
Sonya
Nazeebo
Uther
Jaina
Varian
Alexstrasza
Greymane
Leoric
Deathwing (Required Level: 5)
Yrel (Required Level: 10)
Qhira (Required Level: 15)
Tassadar (Required Level: 20)
Source: https://heroesofthestorm.com/en-us/heroes/
Heroic Deals will be updated once available - but for now, check the current ones - note that Hunter Mecha Dehaka might very like expire today as a Limited-Time Item, as we're getting Spectral Butcher.
Currently in the Nexus is updated (“Free Hero Rotation” link in the top left corner).
Predictions can be seen either as a Result of this Week, or for Future Rotations/Sales.