I am not sure the new rules cover it and it may be that I have nto learned the old rules yet.

A Player controls Thalia, Heretic Cathar, their opponent controls Kalitas, Traitor of Ghet.
Thalia dies and Opponent creates a zombie token. I thought the zombie enters the battlefield untapped as one event (death) is replaced by two events (exiling and creating a token).
I was told I was wrong and ‘exiling + token’ is actually a single event as it replaces a single event and Thalia's static ability affects it. Thus the token would enter the battlefield tapped.

Which is correct and what rule describes such interactions?

Hi,

Thanks for your question. Kalitas has a single replacement effect that both exiles the opponent's creature and creates a token, not multiple replacement effects. The replacement effect does multiple things, but it's still one replacement effect (you can tell because there's no line or paragraph break in the ability). So yes, because of the way replacement effect works, when Thalia would die, before Thalia actually leaves the battlefield, we apply the Kalitas effect to have Thalia go to exile instead of the graveyard and create a token, then (since Thalia still has not left the battlefield yet), we apply Thalia's ability to the token entering. The end result is that Thalia ends up exiled and the token that was created enters the battlefield tapped.

Thanks,
Nathan Long
Magic Rules NetRep