Function spell_backfire

src/spell.c:1180–1217

attempting to cast a forgotten spell will cause disorientation */

/* attempting to cast a forgotten spell will cause disorientation */
staticfn void
spell_backfire(int spell)
{
    long duration = (long) ((spellev(spell) + 1) * 3), /* 6..24 */
         old_stun = (HStun & TIMEOUT), old_conf = (HConfusion & TIMEOUT);

    /* Prior to 3.4.1, only effect was confusion; it still predominates.
     *
     * 3.6.0: this used to override pre-existing confusion duration
     * (cases 0..8) and pre-existing stun duration (cases 4..9);
     * increase them instead.   (Hero can no longer cast spells while
     * Stunned, so the potential increment to stun duration here is
     * just hypothetical.)
     */
    switch (rn2(10)) {
    case 0:
    case 1:
    case 2:
    case 3:
        make_confused(old_conf + duration, FALSE); /* 40% */
        break;
    case 4:
    case 5:
    case 6:
        make_confused(old_conf + 2L * duration / 3L, FALSE); /* 30% */
        make_stunned(old_stun + duration / 3L, FALSE);
        break;
    case 7:
    case 8:
        make_stunned(old_stun + 2L * duration / 3L, FALSE); /* 20% */
        make_confused(old_conf + duration / 3L, FALSE);
        break;
    case 9:
        make_stunned(old_stun + duration, FALSE); /* 10% */
        break;
    }
    return;
}

staticfn boolean
spelleffects_check(int spell, int *res, int *energy)