An Analysis of the "Defensive Properties" of Creatures in Delta Green

WARNING: This post sort of contains spoilers for some creatures and mechanics in the Handler's guide. If you wish to remain unspoilt as an Agent, read no further.

Delta Green is filled with various critters, some unnatural, and some completely mundane. However, all of them usually have what the Handler's Guide calls a "Defensive Property." This blogpost exists to expand upon the "Creating Your Own Unnatural Threats" chapter. I think it's a good resource, but it glosses over the finer details of DPs, plus I have my own bones to pick with a few of them.

Armor is the weakest DP. It's completely mundane and can either be circumvented with Armor Piercing attacks, called shots, or successful Lethality rolls. A slightly higher tier of Armor exists that cannot be avoided with a called shot, like that of creatures with Unnatural Biology. Though technically mundane creatures can have unavoidable Armor, as their Armor is often described as originating from their tough skins or hide.

Unnatural Biology is roughly on par with Armor. Presumably it negates the Headshot and Stun called shot options found in the Agent's Handbook. Though, I know a few Handlers who interpret it to mean that the creature is immune to Stuns altogether. On the one hand, this can create the uncanny effect of blowing huge chunks out of a creature while it still advances on you. On the other hand, it can turn monsters into boring bags of hit points. Plus, most unnatural creatures have a lot of HP anyway, so eliminating half of it in one go is still pretty impressive. Part of the Stun might come from the shock of actually being hurt, rather than the incapacitating power of the attack. As for headshots, I'd apply that on a case by case basis. If you're going to take the time to try to shoot a Deep One in the head, sure, you'll have a greater effect. As far as I'm concerned, Deep Ones need heads. However, shoot a Mi-Go or Dimensional Shambler in the head and you won't have any greater effect. You might make it more difficult for the Shambler to slurp up your blood, though. If you're still unsure about making unnatural creatures susceptible to Stuns, I'd suggest the middle ground of them only being Stunned when they take half their total HP in one attack, rather than their current HP. This keeps them vulnerable, but gives them some staying power when they're on low HP.

Though, I'd also suggest taking a leaf out of CoC's book, specifically the section it has on fighting monsters. It recommends giving monsters alternate goals besides killing the PCs or just having them flee when they're hurt rather than stand and fight to the death. A monster that escapes can be just as scary as a monster that just won't die.

Next up we have Huge, another mundane property that animals, but not humans, can possess. It's not incredibly powerful, but it does one important thing: negate auto-kills from successful Lethality rolls. However, it's still taking damage equal to the Lethality rating, which not only is a lot of damage, it's also consistent damage. In combat, consistent damage can often be more dangerous than more variable damage. Compare 1D4+1 to 1D6. They have the same average damage, but the former will always deal at least 2 points of damage. 

After Huge we have Persistent. I put it above Huge because while it still leaves the creature vulnerable to successful Lethality rolls, taking half damage from all attacks basically doubles your HP. No creature in the HG possesses this ability purely, most having the lesser form where certain types of damage (fire in all the cases) bypass this defense. One, the Wendigo, actually has a more powerful form, combining it with Resilient, so that it not only takes half damage, but is shielded from successful Lethality rolls as well. I think this is a bit silly (especially since the advice in Creating Your Own Threats advises against combining DPs like this). However, you could interpret the text of ICY VITALITY as meaning that Lethality attacks deal full damage, since they are not really "normal damage."

Out of Phase comes after Persistent. OoP also basically doubles your HP, but by making it so all attacks have a 50% chance to just miss. This is theoretically more powerful because Delta Green rounds up, so with Persistent, you're always taking at least one point of damage. Additionally, it effectively halves Lethality ratings, as successful Lethality rolls only take effect if an even number is rolled. Curiously, the Mi-Go possess a lesser version of this DP, as they are still vulnerable to successful Lethality rolls, even if the roll is an odd number. I'm personally not a fan of this ability, as not only can it make fights drag on, but there's no way to hint at it without metagaming. With Persistent, you can at least say "you're clearly hurting it, but just not as much as you might hurt an ordinary creature."

Resilient is in a strange place because while it doesn't double a creature's HP, it does protect them from Lethality rolls, only taking damage equal to the rating on a successful roll. I'd value it at somewhere between Persistent and Out of Phase. I don't have much else to say about this ability. It can stop creatures from being one-shot, but still weapons with higher Lethality ratings are still more dangerous.

A handy dandy chart

Keep in mind that these averages don't represent the full picture. A creature with 45 HP looks like it might take two hits from a 45% Lethality weapon to take it down. However, there's a 45% chance that the attack does 45 damage and just instantly destroys it. Averages are always misleading, be careful.

After Resilient, we have Uncanny Matter. Technically, nothing in the HG possesses this DP, only its lesser form where some forms of damage can bypass it. Both the shoggoth and the Dark Young possess this DP, though the former has a more powerful version of it, as it combines it with Resilient. I very very much do not like this ability for the same reasons I only mildly dislike Out of Phase. The reason is because in both instances where it appears, the 'damage type' that bypasses this defense is "any attack with a Lethality rating of 40% or greater." Also magic, but that goes for everything. With Out of Phase, there's nothing you can do to increase your effectiveness short of resorting to magic. However, here, there is something you can do, but it requires even more metagame knowledge than just realizing that the creature is immune to odd rolls for damage. To make matters worse, the breakpoint exists between a a heavy mortar and an anti-tank guided missile. There's no diegetic reason to suspect that the latter might work where the former failed, especially since the former only inflicts 1 HP of damage where the latter can completely destroy the creature or deal 9 or 24 damage on average (depending on whether it also possesses Resilient). You can reach 40% Lethality with vehicles, specifically a Humvee, which is good. Ramming things is fun and has a good risk-reward trade off. However, like with weapons, the breakpoint exists between a big SUV with 35 HP and a Semi truck with 45 HP. Now, an example where the breakpoint works would be when you ram the shoggoth at high speed vs medium speed. At medium speed, you're only dealing half the vehicle's HP in Lethality damage, whereas at full speed, you get access to the full potential of the vehicle's maximum HP as Lethality.

My advice to Handlers would be to just not use this DP. Or if you do, make it so the ways it's bypassed make more sense. For example, the shoggoth enjoys this sort of protection because it's made of undifferentiated protoplasm, so blasting bits of it away with bullets doesn't have the same effect as it would on say, a ghoul, which still needs to be intact to function. However, setting it on fire with a firebomb or a flamethrower, running high voltage currents through its entire body, or more efficiently removing chunks of it with explosives might deal regular damage. Or even emptying your entire magazine in a long spray in an attempt to attack as much surface area as possible. I don't really know what to do for Dark Youngs because they're the spawn of a god and also a complete invention on the part of Chaosium that stuck around because people thought they were cool. Also you could totally beat up Mi-Go with baseball bats in CoC, which is kinda unrelated, but hilarious.

If you really want that Lethality breakpoint for some reason, I'd recommend lowering it to at least 30%. The one reason I can see to not lower it further is if you're lowering it for a Dark Young, because they just instantly die if nailed with a successful Lethality roll. The threshold of 40% is also pretty okay for baby shoggoths and protomatter creatures, as they only have 19 HP, something you can feasibly achieve with 1 HP chip damage. But that brings us to my proposed replacements.

Transcendent Flesh: The creature only takes 1 HP of damage from normal attacks. If the attack inflicts a Lethality rating of less than 40%, a successful test deals damage equal to the rating, while a failed test only deals 1 HP. For Lethality 40% or greater attacks, a successful Lethality roll destroys the creature and a failed roll does 2-20 damage as normal.

Essentially, it's Resilient vs Lethality ratings lower than 40%, and acts as a normal human for ratings at 40% and higher.

Impossibly Tough: The creature only takes 1 HP of damage from normal attacks. If hit with a successful Lethality roll for a rating below 40%, it takes damage equal to the sum of the dice. Otherwise, a failed roll only inflicts 1 damage. For Lethality ratings of 40% and higher, it takes damage equal to the rating on a successful Lethality roll and damage equal to the sum of the dice on a failed roll as usual.

This isn't that much of a change from the shoggoth's Plastic vs sub 40% rating attacks, only an extra 0.5 to 2 points of extra average damage, but it does make it so successful Lethality rolls inflict more damage, a mechanic that the players don't have to metagame to know about and that is also easier to telegraph. "Your bullets spray ineffectually across the roiling mass, putting holes in it that are quickly filled by the surrounding mass," vs "A concentrated spray obliterates a chunk of the creature. It almost seems to recoil from the attack."   

Before we get to Transcendent, we have a Mysterious Unnamed Defensive Property. Or as I like to call it, Warded. This causes all Lethality rolls to fail and just inflict normal damage. Nothing in the HG innately possesses this ability, as it can only be gained by casting Exaltation of the Flesh (Delta Green's version of CoC's Flesh Ward) on oneself. None of the creatures even have this spell as one of their suggested Rituals. Anyway, it's not necessarily more powerful than Uncanny Matter, but the ability to just ignore the Lethality mechanic so completely is incredibly powerful. A wizard could use this to survive a nuke (it used to be in the AH at 99% Lethality IIRC) or even the disinterested swat of Cthulhu.

Transcendent is the most powerful DP, and curiously, very few things in the HG actually have it. Everything possesses its slightly weaker form where the creature (but more often god) is immune to everything but a few special types of attacks. All the Great Old Ones fall into this category with the exception of Azathoth and Ghatanothoa who are both fully Transcendent. The former's Transcendence goes unremarked upon, while the latter is because it is only an apparition of its true form. Curiously, the Slimes of Tsathoggua are technically lesser-Transcendent, due to being immune to all damage except for fire and magic. Hounds of Tindalos too (excuse me, Hounds of the Angles), as they take damage from curved spaces.

I hope this post helps prospective Handlers create new monsters for Delta Green, or even just understand the existing ones better.