return roll_dice(3, (1 + you.skills[skill] + you.skills[SK_EVOCATIONS])/2);

    return (random2(5*(you.skills[skill] + you.skills[SK_EVOCATIONS])/4));

    const int staff_cost = 2;
    if (you.magic_points < staff_cost
        || random2(15) > you.skills[SK_EVOCATIONS])

    if (random2(15) > you.skills[SK_EVOCATIONS])

        dec_mp(staff_cost);