So we played this scenario last night and it is incredibly frustrating. We were playing it as a solo scenario so started at Level 2 since it was #2 in the campaign, but after about an hour without trapping a single spawn we automatically upped to Level 3 as a handicap, and that helped us finish.

Is it just me, or is Cathulu itself a lot easier than its Spawn? The rule about them losing both the oldest stream after each Ghostbuster as well as all of them moving closer makes them seem a bit overpowered for a class 2 ghost.

We've determined that you have to be level 3 at the very least to even attempt to take them out so you have enough actions to keep stream tokens on them for the next buster.

The appendix also indicated a variant rule where you can change the turn order each round, this would have helped last night since it would have helped coordinate attacks on them.

If you've beaten this one, what's the best way to go about it?

Also- Cathulu himself- does terrain not affect his movement? He seems too big to care about walls so we made it that he just moved through them, but it wasn't stated anywhere specifically, and if this is the case, thematically speaking, wouldn't any walls he pass through no longer exist, removing the obstacles from the GB themselves? I may implement this as a house rule and use some kind of rubble marker to indicate where he's been traveling.