shub-niggurath research encounter question

By cwlborg, in General Discussion

Hi there,

I have a rules question about one of the Shub-Niggurath research encounters from the Forsaken Lore expansion. In the wilderness section it says something like "discard a defeated investigator sheet, then a Goat Spawn ambushes you ...Advance Doom by 1 if you don't defeat the Goat Spawn".

What happends if there are no defeated investigator sheets? Do you still get to fight a Goat Spawn? Or do you simply advance doom by 1 because you did not defeat a Goat Spawn?

Basically it's about card effects that are linked with the word "then". I could not find anything in the rules about that.

Any insight / opinion is appreciated.