Sacrifice X : discard X card from your hand, you get the bonus effect. You draw X cards less at the next draw phase.
it's explained here :
viewtopic.php?f=208&t=10779#p103290Citer :
A new key words has appeared in Eredan iTCG: Sacrifice.
When a card that has a sacrifice effect is activated, you can discard the number of cards indicated to activate the corresponding effect, you will draw the same number of cards less on the next turn.
