blank_book
{
    INPUT: leather, 4
    INPUT: paper, 10

    OUTPUT: blank_book
}

the_arcane_harvest
{
    INPUT: leather, 4
    INPUT: paper, 16

    OUTPUT: the_arcane_harvest
}

sporesorcery_tome
{
    INPUT: blank_book
    BLUE_MANA_COST: 200

    OUTPUT: sporesorcery_tome
}

introduction_to_necromancy
{
    INPUT: blank_book
    BLACK_MANA_COST: 100

    OUTPUT: introduction_to_necromancy
}

advanced_necromancy
{
    INPUT: introduction_to_necromancy
    INPUT: paper, 16
    WHITE_MANA_COST: 150
    BLACK_MANA_COST: 250

    OUTPUT: advanced_necromancy
}