"When this card is drawn, you may underdeck it instead to reveal 6. Put revealed lost souls in play and add a revealed evil card to hand. Underdeck the rest. Cannot be negated."
For those worried about the LS underdecking itself every turn so as to never be rescued, please note that when your deck is small enough, it reveals itself and puts itself in play (its ability only works when drawn). Also, because of the "draw" clause, it can't be abused with Gates of Hell.