Nightseekers have a pretty wide array of good stats—STR, AGI, and LUC—accompanied by reasonable TEC, which combines with their LUC to give them a pretty high DS. To balance this out, their TP is pretty low, and they are fragile. Defensively, nightseekers are similar to arcanists, noted class that really wants to be in the back row because they take significant damage from anything looking at them funny. Nightseekers do not have that luxury, unfortunately, since their actual attack skills are melee. Good thing there's no small shortage of defensive options in this game, and that enemies prefer not targeting party members with low amounts of HP.

Welcome to the big reason that nightseekers are so powerful. Ailments are not at all hard to inflict in EO4, and nightseekers' reward for attacking enemies that are afflicted with them is double damage for the first rank of their class skill, and over double damage for later ranks. Even just normal attacks start dealing 200% damage with the first rank of the nightseeker class skill, which is more than the vast majority of Novice skills!

Of course, the main downside to the class skill is twofold: ailment infliction is still, ultimately, random, and ailment duration is also random. If you prefer highly-coordinated burst phases that have little room for error, the reliance on ailments could be frustrating. Additionally, if you're not pairing your nightseeker with an arcanist, then the nightseeker will be stuck having to spend time attempting to inflict ailments on their own. While the Throw skills have high base chances, and nightseekers have high DS, that's still a variable amount of turns where your nightseeker is only using skills that deal a whopping 80% damage.

Even with those caveats, though... It's double damage! At Novice! And it's not like nightseekers are incapable of dealing damage without their class skill, they can function fine even without it.

A very basic attack skill. It's helpful in the earlygame for giving you elemental coverage, if you opted not to use a runemaster in your party—and, if you're not running duplicate classes, then you will be using a nightseeker if you're not using a runemaster. It's a way to quickly kill rollers, deathstalkers, and other phys-resistant enemies, without having to resort to oils. It's possibly helpful for obtaining both of the "kill with ice damage" boss conditionals. One of those has a 50% vuln to ice damage, while the other has 0%.

Biding Slice is the primary damage-dealer of the Novice nightseeker skills. The TP cost is pretty steep for Novice levels, but that's because it's incredibly powerful for Novice levels! At max rank, getting both hits of Biding Slice will deal 380% damage—760% if the class skill activates. Utterly ridiculous, if you ask me.

Now, of course, the second hit activating is by no means guaranteed. However, there's three fairly simple ways to make it much more likely: using a fortress, inflicting blind on the target enemy, or making use of Decoy Sign. Fortresses not only have Taunt at their disposal for manipulation of the aggro formula, they also have Ally Shield, which you can use to near-guarantee your nightseeker won't take any damage after using Biding Slice. I say "near-guarantee" because there's obviously a chance of the fortress being afflicted with a debilitating ailment, dying before an enemy attacks the nightseeker, that sort of stuff.

Blind is also a good choice for getting that extra hit. Nightseekers are already naturally evasive, what with their AGI being extremely high, and their LUC being "just" high, and a blinded enemy would have only 0.33x of their normal hit chance against them. Put simply, it's a pretty safe bet that blinded enemies won't be hitting nightseekers, unless you're dealing with comically high base skill accuracies...which are not really a thing during the Novice levels. They're not even really a thing until Master levels.

If both of the above aren't an option, for whatever reason? Well, Decoy Sign is there. I wouldn't call it particularly reliable, but you can have your nightseeker inflate another party member's aggro. Whether or not that party member will survive the extra aggro, if they're not a fortress, is another matter entirely...but hey, that takes the heat off your nightseeker.

It's better to think of the Throw skills less as attacks that inflict ailments, and more ailment inflictions that can miss, but deal some incidental damage. As attacks, they're bad, but as single-target infliction skills, they are quite good. 70% base chance at max rank is very high, and to top it off, the Throws are incredibly cheap.

As for Sand Throw in particular? Well, as far as the game is concerned, blind is the least valuable ailment, being all the way at the bottom of the ailment hierarchy. As such, a significant amount of enemies aren't especially resistant to having blind inflicted on them, making it a good general-use ailment. It doesn't stop enemies from acting, like paralysis, panic, and sleep, and it doesn't have any innate damage potential, like poison and curse, but it is still a strong defensive ailment, nonetheless. Most enemy attacks, when under the effect of blind, would be lucky to hit a 30% chance to hit. In most cases, they will end up in the 20% or even 10% range. Doesn't work as well if a character's evasion is disabled, of course, but still.

Definitely a good candidate for maxing out early on.

Oh, and one note about the Throw skills, just in general: they do not require weapons to use. While they deal cut damage and show a weapon slash in the animation, you can have any weapon equipped, or even none, and the Throw skills will still be usable.

It's Sand Throw, but it costs one extra point of TP, and inflicts paralysis instead.

Paralysis is ostensibly a stronger ailment than blind, but both are fundamentally "random chance to nullify an enemy action." While paralysis's chance of rendering an enemy's turn useless is, in most cases, lower than that of blind, paralysis can nullify non-attacking skills, which blind cannot.

Honestly, I still prefer Sand Throw just a bit more, due to blind's ease of infliction, but Nerve Throw is also worth maxing out at least at some point. If nothing else, it can serve as a backup class skill-enabler if accumulative resistance makes inflicting blind difficult or even impossible.

Blade Flurry is worth putting a point into early on, to let your nightseeker equip two weapons, and therefore, get the benefits of two sets of forges. Once you get Follow Trace in the endgame, you need to max out Blade Flurry, since the damage of Follow Trace-activated attacks depends on Blade Flurry.

Oh, right, Blade Flurry does something besides enable early subweapons and provide lategame damage. If you max out Blade Flurry early, you can deal (if you have two identical weapons equipped) 360% damage for 0 TP, if you hit a target with an ailment. That's a neat trick, possibly even worthwhile if your trips into the labyrinth are on the longer side, but I wouldn't call it "good" for general use.

(I had to mention subclassing up there, but I won't be discussing it yet. Have patience, I'm trying to keep the early parts of the LP from being information overload.)

If you're not using a fortress, Shadow Cloak has its uses. Complete nullification of an attack is not something to be scoffed at, even if it requires spending a nightseeker's turn on something that isn't attacking or attempting to inflict an ailment. Nightseekers are extremely frail, especially to physical damage; it's the weakness that's meant to counterbalance their myriad other strengths, after all. Nullification of an attack doesn't just mean you avoid the damage, it also cancels any additional effects, such as debuffs or disable inflictions.

If you are using a fortress, though, I'd say you can leave Shadow Cloak alone. Between Taunt and the Shield skills, you won't be wanting for ways to keep your nightseeker unharmed.

Auto-Cloak is neat, and maybe dropping a value point in it could prove useful, but I wouldn't invest more than that. Six skill points is a very steep cost for a 60% chance to use Shadow Cloak, which only works on one attack, at the start of battle.

Decoy Sign is Taunt, the fortress skill, but with the ability to be targeted on any arbitrary party member.

That does sound enticing, since Taunt is comically strong... But, you do have to question why you'd want to direct enemy aggro on a particular party member if you're not using a fortress. Who would you use this on? Landsknechts, who only begin to become really physically durable in the lategame? Bushi, who are most likely losing HP with each action they take? Imperials, who take a significant amount of extra damage on the turn they're using their big attack skills?

Taunt on its own is already comically strong, all that applying Decoy Sign would do is up the chance of being targeted in weird edge cases.

Assassinate is not meant to be used for its damage, which is just barely better than one hit of Biding Slice. No, the instant kill is the real draw here, and I am honestly a little shocked that EO4 gives the player a semi-reliable source of instant death so early in the game. Even without an ailment, the base chance is eye-poppingly high. Kubikiri and Call Tiger, EO3's two "normal" sources of instant death, both cap out at a 20% base chance. Assassinate starts at a 20% base chance, without an ailment.

Sure, Assassinate is single-target, but it's still instant death. Assassinate is horrifically good for random encounters, especially when there's a really dangerous enemy stuck in the back row, where you can't reach them without suffering a damage penalty. Well, guess what, Assassinate doesn't care about that. As long as the infliction chance succeeds, it doesn't matter how much damage the enemy takes, they're dead.

In short: Assassinate good. Worth investing skill points into.

There's a reason that lethal resistance ceased to be a thing after this game.

Shadow Bite deals a lot of damage against ailments, if you couldn't tell. Its damage increase against ailments is independent from the nightseeker class skill, so, uh... Well, if we don't take diminishing returns into account, if you use a rank 8 Shadow Bite against a target with an ailment, with the second rank of the class skill, that would be 1056% damage. For Veteran, that is utterly ridiculous. Hell, it's even competitive with Swift Edge for an endgame damage skill—Shadow Bite costs less TP, and is far less dependent on accuracy/evasion RNG, both because it's only one hit, and does not have an accuracy penalty.

...Well, of course, that 1056% damage I mentioned is assuming that you have no other active damage increases. Unfortunately, for reasons I don't think I can effectively guess at, Shadow Bite's damage increase is subject to diminishing returns, meaning that its effective damage for any given combination of buffs will be lower than that of Shadow Bite. Not by a significant margin, mind you, but enough that I feel it's worth mentioning.

Sleep Throw doesn't have the broad usability of Sand Throw or Nerve Throw, but sleep's not a bad ailment by any means. If you inflict sleep on an enemy, and then ensure that your nightseeker is the one that'll hit them on the next turn, that'll be some big damage.

Sleep bombing is actually one of the instances of Shadow Bite being completely superior to Swift Edge, since all of Shadow Bite's damage will get boosted by the sleep bonus, while Swift Edge will burn the sleep bonus on the first hit. With the nightseeker class skill at max rank, and without accounting for diminishing returns, a rank 8 Shadow Bite would deal almost 2000% damage to a sleeping target.

Unfortunately, I don't really have any kind words for Curse Throw, due to how poor curse is as a player-inflicted ailment. The best I can say in Curse Throw's favor is that one of the bosses has a "kill with curse damage" conditional, and Curse Throw has a high base chance, so it's okay for trying to get that.

Ah, finally, a nightseeker skill that gives them options against big groups of enemies. While it does require a turn of setup, turning the Throws—which, I remind you, are cheap, fast, and have high base infliction chances—into all-target skills opens up a wide variety of ways to render enemy groups helpless. For my money, before you get Master skills, Sand Throw is good for encounter groups that rely on inflictions, while Sleep Throw is best for those that don't.

Well, I already kind of soft-introduced Swift Edge, but...here it is. While it and Shadow Bite do, on average, deal comparable damage against enemies that are suffering from ailments, Swift Edge has a higher potential for damage, if you land that fifth hit, but also requires either evasion-disabling ailments/leg binds, or accuracy boosts, in order to not miss any of its hits. I personally will come down on the side of Swift Edge pretty much every time, but I do also know people who would greatly prefer Shadow Bite's consistency.

Besides the note I made earlier about Shadow Bite vs. Swift Edge with regards to sleep, it's also worth noting that while Shadow Bite and Swift Edge deal comparable damage against enemies that are afflicted with ailments, Swift Edge is absolutely the winner against enemies that are not afflicted with ailments.

Here's one half of the way that nightseekers can completely invalidate random encounters in the latter parts of the game. Venom Throw is comically strong; 80% base infliction chance is absurd as-is, but then 700 base poison damage at max rank. Ailments are guaranteed to last at least two turns on enemies, so if you inflict poison with Venom Throw, that's a minimum of 1402 damage before it wears off. Not only that, but a good amount of bosses in the endgame and postgame are vulnerable to poison more than other ailments, often to the tune of a 40% vulnerability, making Venom Throw an attractive prospect not just for its own damage, but for activating the nightseeker class skill.

Random encounters fare even worse against Venom Throw. Even the toughest random encounters in the game cap out in the low 1000s range of max HP, which lets Venom Throw decimate them within a maximum of two turns, not even accounting for other party members' damage, or even the initial damage of Venom Throw itself.

Oh, and if you're wondering what the second part of invalidating random encounters is, it's Auto-Spread. You'll see it below the next two skills.

Unless you're having another party member feed ailments for your nightseeker to take advantage of, I don't see much reason not to take Foul Mastery. Even just one infliction provides a significant boost, especially at max rank, and it's not like inflicting ailments with the Throws is difficult.

Another huge damage boost for nightseekers? Etrian Odyssey IV, you shouldn't have.

I'll have more to say on Follow Trace once we unlock subclassing, but suffice to say, maxing out Follow Trace—and Blade Flurry—is a complete no-brainer of a skill point investment decision.

There, this is the second way nightseekers can invalidate lategame and postgame random encounters. If you've got Venom Throw maxed out, and Auto-Spread activates, well... That's just kind of it, for most encounters. Survive whatever gets thrown at you on the first turn, and the enemies will probably die.

Nothin' personnel, pardner.