A case assignment rule can contain up to 3000 rule entries, including 300 formula rule entries, which contain the conditions a case must meet to be assigned to a designated assignee. A case assignee can be a user or a queue.
Does this mean that 3000 rules can have criteria for each and there is only a 300 limit if you create a formula?
Answer from Support:
So when we click on the assignment rule name simply under assignment rule then we can see the total number of rule entries. There is a column named order which shows the count of rule entries and as mentioned in the documents there limit is 3000 rule entries, including 300 formula rule entries which means up to 300 formula rule entries can be added with up to 2700 basic criteria based rule entries.