The single most confusing stat inThe First Descendantis Defense. Some characters can achieve Defense values in the hundreds of thousands, yet the stat can seem downright useless under certain situations. It’s also impossible to figure out what the stat actually does in-game.

It turns out that Defense is a simple damage mitigation layer that every Descendant has access to, but its exact values are tied to a formula that’s never explained in-game. Fortunately, we’ve done enough testing to get a rough idea of how Defense actually scales and how useful it is. Let’s dig into how Defense works and answer an age-old question: Is Defense worth scaling?

Ajax’s defense stats in The First Descendant.

How Does Defense Work?

Defense (called DEF in-game) is one of your main sources of damage reduction in First Descendant, mitigating all non-attribute damage by a certain percentage.The more Defense you have, the less damage your HP and shields receive.Increasing your Defense will reduce all incoming damage,excludingelemental damage, but you’ll start to experience diminishing returns the higher your Defense rating goes.This stat is heavily front-loaded, so you only need minimal investment to see major returns.

The Defense Formula

From our testing, the formula below is the most accurate model we could create for calculating your effective damage reduction (DR) from your DEF rating. This isn’t the exactformula—values are off by ± 1%—but it should give you a fairly accurate value.

Damage Reduction = 0.013 * ln(0.00161 * DEF + 1)

A Google Sheets spreadsheet with damage received values from Dead Bride based on current DEF rating.

Most Descendants have a DEF rating of roughly 2K at max level, granting 19% damage reduction (DR for short). you may easily add 4.6K DEF to your build with a single external component, bringing your DEF rating to 6.6K or 31% effective DR. Throw on another component, and now you’re looking at roughly 38% DR. You can see that the jump between DR values (19 ⇾ 31 ⇾ 38) isn’t linear. That first module drastically increased your DR, while the second module was slightly less effective.

So how much Defense is enough?Based on our testing, you want at least 6,000 DEF.This will give you 32% DR and requires virtually no investment. A single affix on your Memory external component, paired with a Level 40 Descendant, should hit 6K DEF. Additional Defense is generally less effective than adding flat HP to your character.

Screenshot of [Hard] Dead Bride’s base stats in The First Descendant.

Defense Breakpoints

These values were obtained from[Hard] Dead Bride.

Elemental resistances use the same values and exclusively mitigate elemental damage.

680

Stats for [Hard] Executioner in The First Descendant.

10%

2,300

a closeup of Ajax in The First Descendant

20%

6,490

First Descendant Ajax Modded For HP And Defense

31%

13,125

First Descendant Sensor Module With Chill Resistance Affix

40%

29,000

First Descendant Ajax In Bubble Shield

50%

63,000

60%

92,600

65%

As you can see, your DR falls off a cliff past 30K DEF, requiring roughly 2.2x your current DEF rating to gain an extra 10% DR. It doesn’t require much build investment to reach 13K, but achieving 30K+ will require the use of Defense modules. In almost every case, you’re better off equipping a second HP module. To explain why, we first need to talk about EHP.

How We Gathered Data For DEF

Testing Methodology And Data

For this article, I tested over 50 DEF values against [Hard] Dead Bride and [Hard] Executioner. This let me test how DEF works against non-attribute damage (Dead Bride’s cannon attacks) and elemental damage (Executioner + Dead Bride’s mechanics). Executioner uses a mix of elemental and physical damage.

To ensure no weird scaling mechanics are added in Hard mode, I also did a few tests on Normal difficulty. Damage values were consistent across both modes.

Calculating DR was fairly straightforward:

DR = 1 - (Incoming Damage / Base Damage)

To calculate base damage, I simply looked at theTFDToolswebsite. This pulls data directly from the API and displays it in a clean interface. As you may see, [Hard] Dead Bride’s Firearm ATK is 353 at Level 103, which is her level when you attempt the fight solo. Her arm cannon deals twice the listed Firearm ATK damage, so her base damage is 706. The highest damage value I recorded during testing was 704 (75.36 DEF), so the base damage value seems accurate.

With all the data collected, I plotted my recorded values in Desmos and tested various regression models. If you’re interested,you can check the graph here. Surprisingly, the best fit for the damage values was alogarithmic model,nota power model like the community had previously theorized. If you look at the nodes above (the red dots), they fit the logarithmic model (blue line) much better than the power model (red line) in the second image. I cleaned up the values and got this formula:

The formula itself isn’t perfect, but it gives a fairly accurate estimate of how much DR you’ll receive from your DEF rating.It’s unclear if enemies use the same formula, seeing as how certain bosses like Pyromaniac get over 400,000 DEF in Hard mode—which is about 84% damage reduction with this model. Elemental resistancesdouse the same formula, however, but they apply to elemental damage only.

Some bosses, such as Executioner, will deal a mix of non-attribute and elemental damage. In these cases, you need to run a mix of DEF and elemental resistance to fully mitigate the damage. For example, the Executioner’s total damage is roughly 45% electric and 55% physical. DEF values seem to be half as effective on this boss, but once I started to use elemental resistances, the formula began to work as expected, proving that DEF does not mitigate elemental damage.

What Is EHP?

EHP is an acronym for “effective health pool,” which isyour character’s total health value multiplied by your damage resistance values.This is a more accurate way of determining your character’s survivability. In simpler terms, we can use math to determine how many hits our character can take.Once we figure out a build’s EHP, we can compare EHP values against one another to see which build is truly the tankiest.

EHP = (HP + Shields) * (1+ total DR)

For example, if you have 1,000 base HP, no shields, and a total of 33% damage reduction, you’d have 1,333 EHP. This applies to shields as well as health. If you’re playing Kyle and have 8,000 Shields and 50% effective DR, Kyle’s EHP would be 16,000.

Calculating Total DR

The confusing part is calculating your effective DR.Damage reduction stacksmultiplicatively, not additively.You calculate it with this formula:

Total DR = 1 - (1-x) * (1-y) * (1-z)…

Exclude elemental resistances from the formula. It mitigates a different damage bucket.

Each variable in this equation represents a source of damage reduction. For example, let’s say your DEF gives you 30% DR, and you have two modules equipped that grant a total of 20% DR—generic DR sources from modules stack additively. The formula would look like this.

Total DR = 1 - (1-30%) * (1-20%) = 44%

You simply add a (1-x) to the equation for each new source of DR you’re adding to the build. HP and shield values can be taken straight from your Descendant’s stat page, so calculating a build’s EHP should be fairly straightforward.

You have three methods of scaling EHP:

In general, the best way to scale your EHP is by increasing your health.Shields in First Descendant have poor base values, worse module scaling, and lower flat values from external components. Descendants generally have higher base HP values, and external components have stronger max HP modifiers. Modules that scale HP tend to have higher percentages as well.

Is Scaling HP Better Than Defense?

Yes, it is always better to scale your HP over your Defense.Unless you are playing as Ajaxor a Descendant who gets added value from their DEF rating, you willalwaysgain more EHP from scaling your HP than your DEF. Now that we have the formulas for calculating EHP, we can prove this with some basic arithmetic.

The bar graphs above showcase Freyna’s EHP (excluding shields) with every popular external component configuration. Each bar represents her EHP with two modules equipped:

I tested multiple sets of modules to showcase the EHP differences between using two min-max survivability modules versus running a secondary hybrid module like Spear and Shield.The graphs above make it clear that HP scaling is the most effective means of scaling your EHP.Across all component configurations and module combinations, focusing on your HP always leads to more EHP.

However, that doesn’t mean Defense is completely useless.If you focus on scaling your HP, you should always use a Memory component with a gold +DEF modifier.This will increase your EHP by roughly 10% for most Descendants. The highest affix value you may get is 4,264, as shown on theTFD Data Compendium.

Elemental Resistances

Elemental resistances are also worth investing in, provided you’re fighting Void Intercept bosses.An external component can grant up to +3,858 resistance, which mitigates that damage type by roughly 25%. The opportunity cost might seem high, but if a boss is dealing an even split between elemental and physical damage, that’s an easy 12% DR from a single stat on an external component. Don’t sleep on them.

Resistance Modules

Don’t use dedicated elemental resistance mods on your Descendant. The values are pitiful and take up valuable module space. Instead, aim for resistance affixes on your external components.

For reference, each component can roll with one resistance type.

How To Make A Tanky Build In The First Descendant

Now that we understand how Defense and EHP work in The First Descendant, let’s put that knowledge to use. Based on my findings and everything we covered, here are the key takeaways for building a tanky character: