In order to make this achievement fair to users who already purchased a Black Rook membership, the bonus code rules have been slightly changed.

Since today, a bonus can be applied only if a Brain Rook or higher membership level is purchased. Otherwise it would be possible to get a Black Rook for the price of 7 Brain Knight membership which is, actually, very low amount.

Of course, if someone got a bonus for a Brain Knight order in the past, these achievements will not be deleted.