Monstrous Design

I’m finally sitting down to take a serious stab at D&D 4E monster design this week. To make things easier on myself, I’m starting with a 4E conversion of a famous movie monster that I already rolled up for d20 Modern: The Xenomorph from Alien/Aliens.

First Impressions

Let me say right off the bat that, without looking under the hood, I love the idea of exception based design. As I began to familiarize myself with the monster-building tools (DMG1, MM3, Erratta*), I pretty much decided that I could ignore the math and the level of the creature until the last moment to focus on what makes the creature unique and interesting in a fight. So long as I keep the intended tier in mind, I get to play with the fun stuff up front and the rest takes care of itself.

(*As I’ve previously explained, I’m not a DDI subscriber and I prefer to work from the books.)

The funny thing about this approach to monster design is that I get the impression that math doesn’t really matter at all in the game. Its really the number of options that you give the monsters and players that change how the game is played. It should be possible to create monsters that scale through all three tiers with minimal changes to their powers (but what’s the fun in that?).

The other fun thing about 4E monster design is that it seems to be fair game to express a racial feature through a series of different powers or traits that appear on different versions of the monster. All Xenomorphs have acid blood, but it has different effects based upon the different roles of the monster.

By comparison my d20 Modern version of the Xenomorph starts to pale against these possibilities.

Chosing Levels, Roles, and Features

To start, I want a list of the different versions of the creatures that I want to create so I can move my ideas around to see where they best fit. Since I decided that the actual level of the creatures don’t matter until the very end, I’m just making a note of the tier that I expect they are best suited for. All Xenomorphs are Aberrations (which I still have to re-read on the Far Realm so I can put the monster in context with the 4E world).

Facehugger (embryo) – heroic tiny minion lurker. Grapples & Impregnates (treat impregnation as a disease?)
Chestburster (larva) – heroic tiny/small minion lurker. No special features (end phase of a disease)
Drone – heroic medium minion skirmisher. Swarm tactics, self-sacrificing
OR heroic elite lurker. Divide & conquer. Head-biting. Unnerving presence.
Warrior – heroic/paragon large brute. Head-biting, Tail Whipping. Rending claws.
OR heroic/paragon large soldier leader. Protects drones. Covers retreats. Unnerving Presence.
Queen – paragon huge brute/controller. Unnerving presence, summon swarms

Also, I need a list of potential effects for acid blood and for the xenomorph’s ability to change its abilities based upon it’s host.

Acid Blood: The creature bleeds a potent acid that burns through equipment and weilder alike.

  • Ammunition that inflicts damage on the xenomorph is destroyed upon impact.
  • Weapons and implements that inflict damage with a melee attack or thrown as part of an attack begin to corrode (save ends). An item that fails its first saving throw is weakened. Attacks made with a weakened item deal half damage. A weakened item that fails a second saving throw against corrosion deteriorates further and becomes useless.
  • Items may gain a bonus to their saving throw against the acid blood equal to their magical bonus.
  • Any creature dealing damage to a xenomorph with a natural weapon takes ongoing 10 acid damage (save ends). The first time that a creature fails their saving throw against the acid, it is weakened until the end of the encounter. Creatures who do not take damage from the acid due to immunity or resistance are unaffected.

Of course, I may not use all of it. These ideas will be spread out over the entire line of xenomorphs—no one of them will have exactly the same properties of the other.. to keep players guessing!

Adaptive Physiology: Drones, warriors, and a Queen may have additional powers or features based upon their role and the origin of the host that birthed it:

  • Aberrant: ?
  • Elemental: ?
  • Fey: ?
  • Immortal:?
  • Natural: ?
  • Shadow: ?

Additionally, the creature may share one or more physical features of the host: quadraped/biped/wings/fins, low-light/darkvision.

As you can see, I’m still brainstorming.

First Draft

By now, you surly know that I’m not very far into the process. But here is the Facehugger and what comes after:

Embryo Tiny Lurker Minion


Acid Blood: If the xenomorph takes damage while in the same square as a creature, that creature takes ongoing 5 acid damage per tier (save ends).

Standard Actions

Lunge (At-Will * Melee touch) Target: Once small, medium, or large creature within 2 squares. Attack: Dex vs Refl Hit: The xenomorph shifts into the target’s square and grabs it. Miss: The xenomorph slides into a square adjacent to the target.

Move Actions

Implantation (Daily * Melee) Target: one creature grabbed by the xenomorph. Attack: Dex vs Fort Hit: The target falls unconscious until the grab is ended and is impregnated (see below). The xenomorph dies at the end of the encounter. Aftereffect: Target creature is unconscious (save ends).

Triggered Actions

Choke (Triggered Action): If somone attempts to end the grab, the xenomorph’s target loses 1 healing surge. If the creature has no healing surges, it falls unconscious until the end of the encounter.

I broke a minion rule here, the facehugger has a few effects to keep track of. Xenomorphs are ambush predators and they use the same tactics when seeking a host. Lunge attempts to allow the xenomorph an ambush without dealing with awareness and initiative. Choke is pure movie flavor and, of course, it is bad form to kill off the host of your child while it’s gestating. Implantation seems too easy for the monster, but I hope that this is balanced by tracking the gestation period as a disease. I still need to follow up on grab rules to see how feasible the attack really is.

Impregnated Host (Level 1+ disease)

You are impregnated with a xenomorph larva. It grows rapidly and batter’s it’s way through your chest, killing you in a matter of hours or days.
Endurance: Improve DC 20 + 1/2 embryo’s level. Stable DC 15 + 1/2 embryo’s level.
Cured <~> Initial Effect: Target is weakened. <~> Target does not regain healing surges after an extended rest <~> Final State: A larva batters it’s way out of the target’s chest, killing it. The larve is of an equal level to the target.
Cure Disease can remove the larva. Alternatively, the players can engage in a difficult skill challenge to cut it out of the host.

Compared to the DMG examples, I made my DCs 5 higher. Within the context of a horror movie monster, I felt the higher DC was appropriate. After re-reading the cure disease ritual, I decided that its risks were interesting, so why not explicitely allow it?

The chestburster that emerges is intended to be at the same level as the host. But this is probably the least interesting version of the xenomorph, so I’m saving it for last. I’ve considered not statting it up at all!

I like the drone minion! I could have made a swarm but a literal horde of these sounded more interesting.

Drone Skirmisher minion 4


Venomous Sting: Creatures flanked by a Drone are slowed.

Standard Actions

Claw (At-Will; Standard Action * Melee basic) Target: one creature. Attack: Dex vs AC. Hit: dmg

Triggered Actions

Sacrifice (At-Will * Acid; Reaction * Melee) Trigger: When the Drone dies. Attack: Dex vs Refl. Hit: Target loses a healing surge.

Sacrifice is the Drone minion’s version of acid blood. Losing a healing surge sounds excessive but given how strong the acid is supposed to be, it feels appropriate. I’m remembering Aliens and the marine’s retreat to the armored car. I want that affect on my players!

I’m working on the other drone (elite lurker) and the warriors now. It’s a wonderful challenge to visuallize how these behave differently in combat and to come up with new powers to express that. It’s more work, I think, but also more entertaining to do than in previous systems. I hope to have the full suite of 4E xenomorphs available in late July.


~ by Hunter Rose on June 10, 2011.

2 Responses to “Monstrous Design”

  1. hey hey!

    Quick notes:

    + Aberrants have precedentfor being the de facto monster origin type for aliens and space-beasts. I’d go with that. Not that it makes a big difference in mechanics or anything.

    + The attacks should be keyed to Level, not an ability score. So, for example, “Attack: Dex vs AC” should probably read as “Attack: Level + 5 vs. AC”

    I like the idea of a Modern game with the Aliens as antagonist. Could lead to some really awesome adventures!

    • Yes, They are definitely Abberants.–by definition in Modern/3E and by design in 4E. I want to make them a product of the Far Realm. Originally, I had them gain no bonuses from ‘hatching’ from other Aberrant monsters so that would be their base abilities/appearance, but I took it out when writing this because I am sure that I could be more creative than that.

      I haven’t reverse engineered any MM3 monsters yet, but I though that they still get ability modifiers to attacks in addition to Level +5 (or +3). In the DMG, there’s a section about choosing ability scores and what the ability tied to the primary attacks should be. The published errata doesn’t contradict this, so an ability mod to attack is at least implied.

      I would love to play in a Modern campaign with Aliens. I balanced my d20 Modern version against low-level civilians because that’s what you see in the movies. Predictably, space marines tear them up easily but the well-armed and forewarned party’s problem isn’t the beast, it’s the circumstances: uncooperative NPCs, betrayal, time limits, logistical problems, and so on. I think that the monster makes for a great campaign up through mid-levels.

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