At Series B things are more figured out in a company and they should be focused on scaling and growing. So frankly I'd be fairly unlikely to accept 30% below market from a Series B company, however you didn't specify if the base was below market or just below your current comp so hard to judge. You also need to make sure you are comparing apples to apples as far as comp.

Stock options or the like for a Series B company hold a bit more potential value IMO than a seed or A company. However, they are still essentially worthless unless and until the company is acquired or goes public. So you need to evaluate them as such. And a company not telling you the pool size or percentages etc is not being very transparent so I'd expect anything they give you to become so diluted it is worthless and you should negotiate comp as such. Not saying they are a bad company, just don't deceive yourself about the value of options and in a startup transparency around this type of info is pretty critical.

My 2 cents, don't go to a startup as an employee if you are trying to make money. Go to a startup because of the experience and chance to really put your mark on something as well as learn new skills etc. At Series B, that ability is starting to diminish some but still exists, so you have to judge the company and team on if you'd be happy. Just be cautious of low ball offers and promises of riches to come because in all likelihood they won't happen.