// A first step towards to-hit sanity for beams. We're still being
// very kind to the player, but it should be fairer to monsters than
// 4.0.
bool test_hit(int attack, int defence)
{
    return (random2(attack) >= random2avg(defence, 2));
}

                if (beamHit < dodge)

                if (!test_hit(beamHit, dodge))

                if (beamHit < dodge || you.duration[DUR_DEFLECT_MISSILES])

                if (!test_hit(beamHit, dodge) || you.duration[DUR_DEFLECT_MISSILES])

    if (!engulfs && beam.hit < random2(mon->evasion))

    // FIXME We're randomising mon->evasion, which is further
    // randomised inside test_hit. This is so we stay close to the 4.0
    // to-hit system (which had very little love for monsters).
    if (!engulfs && !test_hit(beam.hit, random2(mon->evasion)))