Question about Sif connecting to AotA(dlc)

Hello I need some info about some stuff before I do something wrong.

I want to join the darkwraiths(trophy hunt) but I have too kill Sif for the ring to kill the four kings and get to that weird snakemonster. Does it affect the DLC of AotA? Because I dont wanna screw the game up while at it?

Killing him will not affect what happens in the DLC. However, playing through the DLC will alter the experience in the main game if you keep Sif alive until after you play through the DLC.

Emergence wrote:Killing him will not affect what happens in the DLC. However, playing through the DLC will alter the experience in the main game if you keep Sif alive until after you play through the DLC.

What will happend if I keep him alive I heard about something he's gonna sniff you and than attack just a lil bit different with senerio with screen thats it right?

It's just a cutscene change, yes.