Sets the flood cost of each command specified.
Examples:
/as privilege info cost high
There are some commands that you really don't want used very often, and some commands which don't need to be used often. The LIST command on a large network can be quite expensive to use for both the CPU and your servers bandwidth, and so you'd want to set that command with a high flood limit.
The INFO command is one that has only infomrational use and once issued really doesn't need to be issued again. Where the INFO command is not expensive to the server it is a command that doesn't 'need' to be used and so you could make a case that it should also have a high flood penalty.
In the end you will need to decide what is the right balance for your server and environment.