A monster, as described in the AD&D® game rule books, generally
has a set number of hit dice. Its hit points are usually determined
by recording the sum of the rolls of that number of
eight-sided dice. Some monsters then add a one-time bonus, if their
hit dice are given in the form x + y. Of course, there are exceptions
to this: Dragons, for instance, have a number of hit dice and hit
points which equates to their age level.
The ?set number of hit dice? rule also does not apply to many
types of humanoids, where the number of hit dice may be different
for adult males, adult females, and young of either sex. However,
the system for dragons is the only one that takes into account the
concept of a creature gaining more hit points as it advances in age.
It is not especially difficult to create such a system for other monster
types, and along with that to adjust the system for experience-point
calculation. By doing this, we can help insure that player characters
get a proper amount of credit for killing monsters with many hit
points ? and also a proper (smaller) number of experience points
for killing younger (and thus weaker) monsters with fewer hit points
than a full-grown adult.

THE GROWTH PROCESS
Let?s begin by looking at the maturation of an animal and a
?monster,? using a tiger and a manticore as examples..
A full-grown adult tiger has 5 + 5 hit dice, armor class 6, three
attacks for 2-5/2-5/1-10 points of damage, and a chance for two
more attacks doing 2-8 points of damage apiece. Now, we start at
the other end of the scale and work up to these figures. Let?s say that
a newborn cub has 1 hit die, armor class 10, one attack (bite) for 1
point of damage and no chance for a special attack. As the cub
grows to adulthood, its statistics will change to reflect its increasing
toughness as an adversary.
Why is armor class included in the statistics that change with age,
and why is the change so great (from AC 10 to AC 6)? Because
armor class reflects not only the natural toughness of a creature?s
hide but also the creature?s ability to move quickly and smoothly to
evade an attack. A newborn tiger does not have the thickness of coat
nor the toughness of skin that an adult would have, and the cub also
does not have the coordination and quickness of a full-grown tiger. It
is within your right as a DM to adjust armor class for an especially
quick or agile animal or monster, just as you would (according to the
rules) for a player character with exceptionally high dexterity. A
healthy, mature tiger that you judge to have exceptional dexterity
might be given an armor class of 5 or even 4.

Growth stages of a tiger

Age	HD	#Att	Bite	Claws	Rear  claws	AC
Newborn	1	1	1	nil	nil	10
1-3 mos.	2	3	1-4	1/1	l/l	9
4-6 mos.	3+1	3	1-6	1-2/1-2	1-2/1-2	8
7-9 mos.	4+2	3	1-6	1-4/1-4	1-4/1-4	7
10-15 mos.	5+3	3	1-8	2-5/2-5	2-5/2-5	6
16+ mos.	5+5	3	1-10	2-5/2-5	2-8/2-8	6

Naturally, not everyone will agree with the specific numbers in
this example; it?s the concept that?s important here, not the precise
way you might see fit to put the concept into practice. I don?t know

how fast a tiger really matures; if you do, then perhaps you?ll want
to use figures that better reflect that reality.

If the example of the tiger is subjective, then this next example is
even more so ? because nobody really knows how rapidly a manticore
matures, do they?

Growth stages of a manticore

Age	HD	#Att	Bite	Claws	Tail Spikes	AC
New born	1	1	1	nil	nil	10
1-3 mos.	2	3	1-3	1/1	6 x 1 pt.	9
4-6 mos.	3+1	3	1-4	1-2/1-2	12 x 1-2	8
7-9 mos.	4+2	3	1-6	1-2/1-2	12 x 1-4	7
10-15 mos.	5+3	3	1-6	1-3/1-3	18 x 1-4	6
16-24 mos.	6+3	3	1-8	1-3/1-3	24 x 1-4	5
25+ mos.	6+3	3	1-8	1-3/1-3	24 x 1-6	4

Having monsters grow up gradually like this gives you more
freedom as a DM when designing encounters. If a single 1st-level
fighter encounters a single tiger, it need not be a full-grown adult
tiger but could be a less powerful youngster. This would make it
easier for the fighter to survive the encounter and defeat the tiger ?
and, of course, this would also mean that the fighter?s experiencepoint
award for doing so would be lowered accordingly. Likewise, if
a group of player characters encounters a group of monsters of the
same sort, there is no reason why all those monsters would necessarily
have the same hit dice and damage capability.

<>

DRAGON, GREEN

MERMAID

SPRITE

THE AGING PROCESS
Now that we?ve taken monsters from birth to maturity, it?s time to
deal with the other part of the life cycle. The DMG provides a system for the aging of player characters; the
handling of animals and monsters in the campaign can benefit from
an aging system, too.

Obviously, we can?t express the effects of monster aging in the
same terms used for characters, since most monsters don?t have
definable scores in strength, dexterity, wisdom, and constitution. But
what we can do is translate the effects of aging into the characteristics
that make monsters what they are ? in other words, hit dice,
armor class, and damage capability.

Suggested alterations to account for aging are summarized in the
following table, which begins at the young adult stage (where the
growth tables leave off) and proceeds through the venerable age
category. The figures given here would probably work best if they
are only applied to monsters of 4 or more hit dice; statistics should
be adjusted downward (closer to zero, or no change) for creatures of
3 hit dice or less.
 

Age	HD	AC	Damage
Young adult	+d4 (d8)	-1 (30%)	+1 or +2
Mature	+d6 (d10)	-1 (50%)	+1 to +3
Middle age	+d4 (d20)	-1 (10%)	-1 to +1
Old	-d6 (d12)	+1 (40%)	-1 to -3
Venerable	-d8 (d10)	+1 (70%)	-1 to -4

How to use this table
Each entry in the "Hit dice" column shows one die range as a
+positive+ || -negative- quantity plus another die range in parentheses.
Roll the type of die indicated in parentheses; if the result is a value
that could be obtained by rolling the other die given, then add or
subtract that number of points from the monster's HP total and
change the monster's HD designation accordingly, if necessary.
    As an example, let's go back to the tiger, which "tops out" on the
    growth table at 5 + 5 HD. In other words, it will have a number
    of HP in the range from 15 through 45, and it will attack as a
    6 HD monster (according to p. 75 of the DMG). The animal will
    not grow any larger physically, but it may gain a few hit points for
    being in the young adult age category: Roll d8, and if the result is 1,
    2, 3, or 4, then add that number to the animal's hit-point total. Also
    add this number to the tiger's effective hit-dice figure of 6, so that
    the resulting value is anywhere from 6 + 1 to 6 + 4 ? and remember
    that if the result is 6 + 4, then the tiger will attack as a 7 HD monster.
    If the d8 roll was greater than 4, then the tiger remains at 5 + 5
    HD and whatever hit-point total the animal already had (but it is
    still eligible for changes to armor class and damage by virtue of
    being a young adult).
The same procedure applies for reductions. If you decree that a
tiger is venerable, then roll d10. If the result is between 1 and 8
inclusive, subtract that many points from the tiger?s maximum hitpoint
total and also adjust its effective hit dice for attack purposes if
necessary. If a 1 or 2 is rolled, the tiger is still effectively a 6 HD
monster; if the result is between 3 and 8, the animal is reduced to a
5 HD monster. (For a subtraction that crosses the ?barrier? between
hit dice, consider 5 hit dice to be equivalent to 4 + 8; in other words,
subtracting 8 from 5 + 5 yields a result of 4 + 5.)
Under the ?Armor class? heading are given an adjustment and a
chance for that adjustment to occur. A young adult has a 30%
chance of having an armor class that is one step lower (better) than
normal; a venerable animal has a 70% chance of having an armor
class one step higher (worse) than the usual figure.
The ?Damage? column gives suggestions for alterations that you
can apply when you deem it appropriate to increase or decrease the
normal damage figure (or figures, for creatures with multiple attacks).
You may wish to rule that a monster is not eligible for an
improvement in damage capability unless it also gains hit points and
a benefit to armor class, or you may assign extra damage capability
to an otherwise normal monster; it is possible that a tiger could have
the usual number of hit dice and armor class, but be able to do more
damage because of extra-sharp teeth or extra-long claws.

HIGHER HIT-POINT TOTALS
Few things are more discouraging to a DM than placing a "terrible" monster guarding an important treasure and then watching the
party blow it away in a few rounds (or sooner). This sometimes
happens if the monster is handicapped by the "glass jaw" of lower
than average rolls for hit points. You rolled the proper number of hit
dice, and lots of them came up 1, 2, or 3. You want to be fair and go
by what the dice dictated (after all, that?s what player characters
have to do), but you don?t feel right about leaving things the way
they are. One obvious solution is to simply roll the dice all over
again, but there?s no guarantee that the second set of rolls will be
any better.

The other way to prevent this problem is to modify how the hit
points are determined -- with the understanding, of course, that this
tactic is only used in special situations where a properly challenging
encounter requires that the monster(s) be tougher than average.
There are two common methods for achieving this goal:

1) Guarantee a better-than-average hit-point total by using d6 + 2
or d4 + 4 for each hit die instead of d8. This has the same effect as
rolling eight-sided dice but then re-rolling any results lower than a
certain cutoff point ? usually 1 or 2, but perhaps as high as 3 or 4
for certain monsters or certain situations.

2) Increase the chances of getting a tough monster by using 10-
sided or even 12-sided dice instead of eight-siders. Before you roll,
decide whether or not you will allow the total to exceed the maximum
attainable with eight-sided dice; a tiger generated with 12-
sided hit dice will have an average of 38 hit points, which seems
reasonable if a tough tiger is desired ? but if you don?t decide to cut
it off at 45 (the normal maximum), then it could have as many as 65
hit points, and that might be going too far. By the way, if you do
decide to allow the hit-point total to exceed the normal maximum,
you should still keep the tiger at its normal hit-dice figure for attack
purposes. Making a tiger with 65 hit points that also attacks as a 14
HD monster is definitely stretching the intent of this advice beyond
the breaking point.

A NEW DESIGN FOR DRAGONS
There's a problem in the way dragons are handled in the rules,
but it has nothing to do with the rules themselves. A system of one
hit point per hit die per age level is fine, but knowing this gives
players an advantage they should not have. The players should not
be able to calculate a dragon's hit points and breath-weapon potential
after the first time the PC party is hit by its breath weapon.
Alas, the rules do inadvertently allow this sort of behavior: If the
players have discovered that a dragon does 28 hit points of damage
with each breath that hits, then a fighter with 29 hit points will rush
forward to get in that one last killing stoke while on with 27 hit
points will run the other way. How to avoid this? Try the reconstructed
dragon. as described below:
 
 

Age  level	HP*	Breath  attacks	Other  attacks
1	d2 x HD	1 (50%) or 2 (50%)	25% of adult
2	d3 x HD	2 (50%) or 3 (50%)	50% of adult
3	d4 x HD	3	75% of adult
4	d4+1 x HD	3 (50%) or 4 (50%)	adult
5	d4+2 x HD	3 (25%) or 4 (75%)	adult
6	d4+3 x HD	4	adult
7	d6+4 x HD	4 (50%) or 5 (50%)	adult +10%
8	d8+4 x HD	5	adult +25%

* -- Also used to calculate damage each time breath weapon is used.

This system makes dragons slightly stronger (more hit points) on
the average, gives most dragons more frequent use of their breath
weapons, and varies claw/bite damage according to age. (Old
dragons don?t get weaker, they get better.) Most importantly, it
considers hit points and breath damage separately; hit points are
rolled once, when the dragon is generated, but damage from a
dragon?s breath weapon is rolled on every attack instead of being a
constant number. Is all of this too much? No, it isn?t. Consider this
example of an ancient (age level 8) dragon with 9 HD:

The dragon will have anywhere from 45 to 108 hit points, with the
average result being 76½. Likewise, each use of its breath weapon
will do from 45 to 108 points of damage ? but that is a variable, not
a fixed amount. The average damage of 76½ compares favorably
with the official system, where the dragon?s breath would do 72
points of damage on each strike. (Optionally, you can retain the
fixed calculation for hit points and still use this system for breath
damage, if you don?t like the idea of an ancient dragon with only 45 HP.)

After one or two encounters with these ?new dragons,? it will be
obvious to players that they can?t dictate their characters? actions on
the assumption that the dragon will do a fixed amount of damage
with its breath. Imagine their surprise when an ancient dragon
breathes for ?only? 50 points of damage in one round ? and follows
that up with a 100-point blast the next time it opens its mouth!

M O R E TACTICS FOR T O U G H E R M O N S T E R S
Monsters can be made more formidable, within the context of an
adventure or an encounter, by simply taking full advantage of the
situation. Give a monster, or a group of monsters, a few allies.
These don't have to be henchmen, hirelings, or slaves. They can be
unwitting or unwilling accomplices.

Let's set up a small group of manticores in a lair. Even by themselves,
the manticores are a threat ? but they don't exist in a vacuum.
Close to the manticore lair is a small wooded area that serves
as home to several flocks of birds. These birds might make a tasty
snack for manticores once in a while, but the manticores are
intelligent enough to realize that killing away the birds is
not in their best interest. When the birds become silent or take to the
air as a group, it doesn?t take a genius to figure out that they were
disturbed by the approach of someone or something. The birds are a
simple, but effective, sort of early warning device.

Now we?ll go one step farther and add a wolf pack that lives
nearby. The wolves may claim some of the food that the manticores
could get otherwise, but they also make a good warning device as
well as being able to attack in their own right. A group of very cunning
manticores might actually aid the wolves (and help keep them
in the area) by bringing them food when times are lean, or by coming
to their aid during a melee. And the wolves might well return
the favor ? imagine how a party might act in the middle of a ?simple
? battle with manticores when a pack of wolves suddenly bounds
into the picture.

The general idea here is that combinations of animals or monsters
present a more challenging obstacle to player characters than if those
adversaries are encountered in separate groups, and this kind of
game is more enjoyable than one in which characters simply run a
gauntlet of one monster type after another.

MORE EQUITABLE EXPERIENCE POINTS
A troll has 6 + 6 HD and is worth 525 XP plus 8 XP
per HP. Thus, a weakling with 12 HP has an XP value of
621, while a "supertroll" with the maximum of 54 HP has an XP
value of 957. What?s wrong with that?

Well, look at it this way. The second troll has 4½ times as many
HP as the first but is worth only about 1½ times the XP.
The problem lies in the system, which gives too high a
base number of XP compared to the number of XP that are awarded
per HP.

Here's one way to remedy the situation while retaining most of
the structure of the existing system.

A. Divide the monster's base xp value in half and
B. then divide that number by the maximum HP it is possible for such a monster to have.
C. Round the result to the nearest whole number and
D. add that number to the "per HP" part of the XP award, and
E. then calculate the new total.

Example one is the troll. The base xp value is 525; half of that is
263 (rounding up on any fraction of .5 or greater). Divide 263 by 54
(the maximum hit points possible) and round the result to 5. Add
that to the value of 8 xp/hp to get 13. Now the experience-point
formula for a troll is 263 + 13/hp. A troll with 12 hp becomes worth
419 xp; a troll with 54 hp becomes worth 965 xp; and a troll with 33
hit points (the average) is worth 692 xp. In the official system, the
figures would be 621, 957, and 789 respectively. The revised system
awards slightly more xp for the toughest possible troll, but gives a
much smaller award for those that are less formidable.

For example two we?ll use the giant squid, a 12 HD monster with
a ?book value? of 2000 xp + 16/hp. Half of 2000 is 1000; dividing
1000 by 96 yields a result of 10, so the new formula is 1000 xp + 26/
hp. Now compare the values produced by each system:
 

HP	Book value	New system
12 (minimum)	2000 + 16 x 12 = 2192	1000 + 26 x 12 = 1312
96 (maximum)	2000 + 16 x 96 = 3536	1000 + 26 x 96 = 3496
54 (average)	2000 + 16 x 54 = 2864	1000 + 26 x 54 = 2404

As with the troll, the new award for a maximum-hp squid is comparable
to the book value (this time it?s slightly less instead of
slightly more), and again the awards for monsters of lesser strength
are substantially reduced.

This system works well for virtually any type of monster, and
helps to insure that player characters don?t receive undue credit for
killing monsters that are relatively easy to dispose of. At the same
time, it doesn?t inflate the value of monsters at the high end of the
hit-point scale, which helps keep character advancement under
control ? your control.

<
TEMPLATE: Growth stages of a

Age	HD	#Att	Bite	Claws	Rear  claws	AC
Newborn	1	1	1	nil	nil	10
1-3 mos.	2	3	1-4	1/1	l/l	9
4-6 mos.	3+1	3	1-6	1-2/1-2	1-2/1-2	8
7-9 mos.	4+2	3	1-6	1-4/1-4	1-4/1-4	7
10-15 mos.	5+3	3	1-8	2-5/2-5	2-5/2-5	6
16+ mos.	5+5	3	1-10	2-5/2-5	2-8/2-8	6

>

<
TEMPLATE:

Age	HD	AC	Damage
Young adult	+d4 (d8)	-1 (30%)	+1 or +2
Mature	+d6 (d10)	-1 (50%)	+1 to +3
Middle age	+d4 (d20)	-1 (10%)	-1 to +1
Old	-d6 (d12)	+1 (40%)	-1 to -3
Venerable	-d8 (d10)	+1 (70%)	-1 to -4

>

" Magical
creatures usually mature quickly (a year or
so at the main), at which stage they leave
the lair with full control of their abilities. "
- Dragon 130.74