The Monster Attack Filter capability
allows you to modify the standard actions when a monster is about to
attack the party. You do this by writing a DSA that modifies the
parameters that are used to carry out the attack.
The parameters are computed in the standard way. Then the DSA is
activated. The DSA will fetch a copy of the parameters, modify
them as desired, then send the parameters back to the runtime engine to
be acted upon. When the parameters are fetched, they are
placed in an array. The parameters are numbered from 0 through 19
in that array. The following paragraphs describe each of the
parameters, its index in the array and how it is computed in the
way. After the description of the parameters we will discuss how
the parameters are used.
 Monster ID. This is the "Indirect Pointer Index" of the
monster group that is attacking the party. It is a unique
identifier among all objects in the dungeon. It can only be
reused if the group of monsters is killed. Then it can be reused
for any type of object that is created during gameplay.
 Monster Type. Giggler, Screamer, etc. See Monster Types
 Monster Index. The index of the particular monster within the
group of monsters that is carrying out the attack. 0-3.
 Monster Level. This is the dungeon level of the monster.
 Monster X. This is the X-coordinate of the monster.
 Monster Y. This is the Y-coordinate of the monster.
 Monster Position. This is the position of the monster within
the cell. 0=NW, 1=NE, 2= SE, 3= SW.
 Missile Origin Position. The position within the cell at
which any missile will be launched. This is not the same as the
Monster Position because if the monster is standing in the rear of the
group (relative to the party) then the missile would hit his own
companion in front. So the Missile Origin Position is moved to
the front of the group (relative to the party).
 Missile Range. This is computed by the following sequence of
Range = Monster Descriptor Byte8 / 4 + 1
Range = Range + Random(Range)
Range = Range + Random(Range)
 Missile Damage. This is set to Monster Descriptor Byte8.
 Missile Friction. This is the amount subtracted from Missile
Range and Missile Damage each time the missile moves.
Standard value is 8;
 Direction to Party. The direction from the monster group to
the party. 0=North, 1=East, 2=South, 3=West.
 Distance to Party. This is what I call Orthogonal
Distance. As the taxi drives. Not as the crow flies.
 Missile Type. An integer specifying whether Firball,
PoisonCloud, etc. See Missile Types.
This is computed from the Monster Type as follows:
Vexirk or Lord Chaos - Random (Fireball 50%) (Dispell, Lightning, Zo,
Poisoncloud each 12.5%)
Slime Devil - Poison
Flying Eye - Random (Lightning 87.5%) (Zo 12.5%)
Zytaz - Random (Fireball, Poisoncloud each 50%)
Demon or Dragon - Fireball
Anything else - No Missile
 Monster Should Launch Missile - Non-zero if the monster should
attack with a missile spell.
Compute with the following sequential steps:
Set to 0.
Set to 1 if Distance To Party is greater than 1.
Set to 1 with 50% probability.
Set to 0 if bits 12-15 of word 14 of the Monster Descriptor are less
 Monster Should Steal - Non-zero if the monster should try to steal
an item from the party.
Set to 1 if the monster is a Giggler.
 Index of hero to damage. 0 to 3.
This index is computed in one of two ways depending on the Monster
word 2 bit 4.
If word 2 bit 4 is non-zero then the index is the index of a random,
If word 2 bit 4 is zero then this is the index of the hero closest to
the monster. Closest
means closest front-to-back (relative to the monster). If
two heros are equally close front-to-back then choose the one of the
two closest left-to-right.
You can modify this parameter. There are three special values:
- 4 means the character leading the party
- 5 means select a living party member at random
- 6 means the living party member 'closest' to the monster
 The ordinal of the Attacking Sound. Zero means silence.
 Disable Time - Set to -1 to mean unused. Perhaps someday we
can do this.
 Unused. Set to -1.
Attack - or - How the Parameters are used.
The sound of the attack is queued. Then we chose the
Type-of-Attack and carry it out. There are three different
Types-of-Attack: 1) Missile, 2) Theft, 3) Physical attack. We will
describe how the Type-of-Attack is selected and then how each type is
First we look to see if the monster should launch a missile (parameter
Monster Should Launch Missile is non-zero). If so, the monster
attempts to launch the missile and we are done. Note that if the
Monster Should Launch Missile then the parameter named Monster Should
Steal is ignored. Note that if the Monster Should Launch Missile
but the Missile Type is NONE then nothing is launched and the attack
totally fizzles (you can completely abort an attack this way).
Second we look to see if the monster should steal an item from the
party (parameter Monster Should Steal is non-zero). If so, the
monster attempts to steal an item and, whether or not it is successful,
the attack is complete.
Lastly, the monster attempts to inflict physical damage.
If the Missile Type is NONE (or illegal) then no missile is launched
and the attack is complete. Otherwise we launch the missile
specified by parameter Missile Type from the location indicated by
parameters Monster X, monster Y at Missile Origin Position. The
missile will trave in the direction indicated by parameter Direction to
Party. Its range and damage will be set to parameters Missile
Range and Missile Damage and its friction will be set to the parameter
The monster will attempt to steal an item from the hero designated by
the paramter Index of Hero to Damage. The theft may or may not be
successful but in either case the attack is complete. Someday we
may use one of the unused parameters to specify which item or kind of
item should be stolen.
The standard mechanisms are used to
cause damage to the hero specified by Index of Hero to Damage.
The attack may or may not be successful. In any case, the attack