Look haaadaaah...
"Only one artifact, covenant, or curse in the artifact pile may be active at a time. Once per turn, you may select one artifact, covenant, or curse to be activated and flip it face up on your artifact pile. The face up artifact, covenant, or curse becomes active and cannot be changed until your next turn. To change the activated artifact, covenant, or curse, you select it and place it face up on the artifact pile and return the other artifact, covenant, or curse face down in the artifact pile. If you choose to have no artifacts, covenants, or curses activated, you may turn the top artifact, covenant, or curse face down."