Question [Question] The Piercing, the Luminite, and the Ichor

[Terry N. Muse]

Hey guys, I've been playing Terraria mostly within a small circle of friends. Was introduced to the concept of hoiks through Yrimir's videos some time ago and began poking around on my own from there. Things like the underlying mechanics of games (and how players learn to make full use of them) never failed to fascinate me before, and I don't think they will any time soon.

Which brings us to the now! During discussion with a friend, I was told that an optimized Stardust Dragon used alongside S.D.M.G. with Crystal Bullets generates the absolute highest single target DPS over the likes of Last Prism. That's beside the point; I now have a summoner character using an S.D.M.G. with Luminite Bullets. While I was going through a routine Moon Lord kill, I noticed that I was firing on the core with the S.D.M.G. while my Stardust Dragon was on it, but my DPS didn't seem to increase. Later on, I accidentally confirmed with a mage character that Stardust Dragon does synergize with Bubble Gun - a weapon with projectiles that definitely don't pierce. I haven't tested the S.D.M.G. again with Chloro or Crystal Bullets, however.

What is the exact nature of Luminite Bullets and their ability to "ignore" piercing invulnerability? Is it that Luminite Bullets simply do not trigger piercing invul, but they will be blocked if another weapon does trigger it? Are Luminite Arrows related? Why does the Terraria wiki say that Luminite Bullets have the lowest base velocity out of all bullet types in the game?

On a slightly related note, I've begun trying out Betsy's Wrath with my mage and primary character. It seems like a solid weapon (when enemies aren't immune to all debuffs...), but it got me thinking, and a few searches later I found someone alleging that defense reduction can cause enemy defenses to go negative. According to them, this means that the Sharpened buff, Shark Tooth Necklace, ichor, Betsy's Curse, etc. can be used against all enemies to their fullest effect. Is this true? Additionally, can I get some advice on how to personally test this in-game?

Thanks for your time.

 

[Programmatic]

Basically, weapons that deal continuous damage to enemies (like the Stardust Dragon or Nebula Arcanum), as well as piercing projectiles (such as luminite bullets or meteor shots), put enemies into a brief invulnerability state after taking damage, in order to prevent the weapon from hitting an enemy on every single frame during which they overlap. There is one separate timer per enemy, as opposed to per projectile, meaning that if a continuous damage weapon or piercing attack is damaging an enemy, then others won't be able to. This is why the Stardust Dragon is blocking damage from the luminite bullets. For the same reason, you should also avoid using piercing ammo on weapons that fire multiple projectiles at the same time.

 

[Terry N. Muse]

I appreciate the timely response. A quick test seems to indicate that Luminite Bullets are exempt from piercing invulnerability in some form.

Tactical Shotgun, with Meteor Shot (Top) and Luminite (Bottom). Piercing invul causes the front dummy to only take damage once from Meteor Shot as expected, but every bullet of Luminite seems to inflict damage at once.

Does this mean that although Luminite ammo can still be subjected to piercing invul, but doesn't trigger it? Or is it something else? While the limits of piercing weapons are fairly well-known, I can't seem to find much specifically about what grants Luminite ammo its unique properties. Has anyone looked at the code regarding these?

 

[fooksie]

The wiki specifies that any piercing attacks will not do damage with the Stardust Dragon active; as for why that is...

The Luminite Bullet (3567) projectile (638) in Projectile.cs resets immunity (along with projectiles 639 and 640) when it successfully hits, but cannot hit if the target is already immune (as by Stardust Dragon triggering piercing invulnerability separately). Therefore, it is subject to existing piercing invulnerability but does not trigger it (more specifically, it seems to trigger then reset it).

that's if I read the code right, which I think I did

 

[Terry N. Muse]

I see. Thank you for the explanation! Do you also know whether defense reduction on enemies can only reduce it to zero, or can it be reduced to a negative value? I'd imagine it's the former, but I'd like confirmation as well.

 

[fooksie]

In Player.cs, Sharktooth Necklace (itemid 3212) gives the player +5 armorPenetration and Sharpened (buffid 159) gives +4 armorPenetration. In NPC.cs, Ichor (buffid 69) and Betsy's Curse (buffid 203) set self.ichor and self.betsysCurse to true.

When calculating damage in StrikeNPC, ichor and betsysCurse subtract 20 and 40 defense respectively, then if Defense < 0, Defense = 0.

However, armorPenetration is converted to raw damage in checkArmorPenetration and does NOT reduce the target's defense (armorPenetration is, basically, just a raw damage boost).

So, ichor and betsysCurse are the only effects out of the ones you listed that actually lower enemy defense, and they cannot lower enemy defense below 0.