You haven't sacrificed a card on this turn.
We recommend you sacrifice cards each turn until you
have at least 5 astral power. Use the right mouse
button to sacrifice any of your cards. Each time you
sacrifice a card your astral power and mana increase
by 1. At the beginning of each turn you receive a
certain amount of mana equal to your amount of
astral power. You can sacrifice only 1 card per turn.