A FL4K build themed around corrosive damage with an emphasis on corrosive-only gear. The only non-corrosive damage sources this build uses are He Bites!, which is for stacking Frenzy, and Hollow Point, which is too good not to pass up (especially on FL4K). Obviously not an optimized build (because it's only corrosive, duh) but it can easily handle most content at M10 (yes, even enemies without armor) with proper FL4K strats.
As a general rule for anointments, ASE splash is best followed by N2M. Consecutive hits, 300/90 and ASE 100 can work as well.
Note: All gear and anointments should be corrosive (if possible) both for the sake of the theme and for maximum Flesh Melter synergy.
- Reflux - This is your best mobbing tool due to its amazing crowd control potential and synergy with Head Count. Note that enemies with Buddy Systems can be chained (they just won't take any damage) so if you see one by a badass or a large group of enemies take out everyone else first before focusing on them.
- Gargoyle - Best for lone enemies. It's very ammo-hungry though so be careful about using it for extended periods of time.
- Breath of the Dying - Great for mobbing provided you can stay out of the way of the orbs. Two things to keep in mind when gearing for this gun: 1. the bullets are not boosted by assault rifle damage, 300/90, Hidden Machine, the Hunter's Eye armor bonus or the DE4DEYE's special effect. 2. Using a grenade/shield elemental anoint can sometimes prevent the orbs from spawning on kill.
- Hornet - Nowhere as good as the Gargoyle but it can still do decent damage at M10 with this build.
- Plaguebearer - Best overall heavy weapon for FL4K due to the multitude of homing projectiles as well as the fact that you can't down your pet with it. The charge is annoying but short enough so that you can get three Fade Away shots in (provided you have Persistence Hunter).
- Sand Hawk - This is probably the best corrosive sniper for a Fade Away build right now (the Complex Root does more damage but the burst fire restriction ruins it for Fade Away). I normally use semi-auto because it has pretty good one-shot potential with Fade Away and an amp shield but really any firing mode will work well.
Unfortunately sliding/shield regen is currently not in the anoint pool so try ASE corrosive, cooldown or terror (provided you have a Ghast Call) for your shield anoint instead.
- One-Shotter' Shield - General best in slot here; great for one-shotting things (as the name implies). I prefer the Pangolin variant because it has the fastest recharge. Get one with corrosive resistance for bonus thematic points.
- Impaler - The spike damage is lackluster even with Mayhem scaling but it's corrosive-only (which goes well with the theme), it has a fast recharge and it spends more time being full than any other shield here which gives it the most synergy with Topped Off. It's also parts-locked and is much easier to find than a One-Shotter.
- Old God - Great for long-term damage but the slow recharge gives it little synergy with Topped Off and with Flesh Melter an extra 20% corrosive damage will do very little. Neither of these drawbacks are really an issue for bossing though which makes it a great choice for that.
- St4ckbot - Because the model is the corrosion color (green). That's literally why it's the main COM for this build.
- Bounty Hunter - More reliable than the St4ckbot but less potential. Note that with this COM and a proper gun you can stack the Interplanetary Stalker corrosive bonus against bosses pretty quickly.
- DE4DEYE - For one-shotting with guns like the Plaguebearer. Also great for top bar-heavy bosses like the Traunts.
- Ghast Call - Does a shit ton of damage and it comes in only corrosion too. Vindicator is the best version but really any roll will work well. The child skulls all home which is great for Pearl stacking and Buddy System destroying. Note that the Ghast Call currently cannot spawn with an anointment.
- Flesh Melter - Not the greatest for bossing but for mobbing with corrosive weapons it's absolutely one of the best choices out there especially if you're using a corrosive weapon with crowd control potential. The exact artifact is up to you; I like Otto Idol for the survivability but that's just me.
- Pearl of Ineffable Knowledge - Use this for bosses. The Ghast Call is great for getting stacks quickly, provided you're actually able to hit your target with the initial throw.
Obviously there's the skill tree below but I'm including this section just to justify certain skill choices I've made.
- Fade Away - Both Rakk Attack! and Gamma Burst deal elements other than corrosion so go with Fade Away (at least until we get Gravity Snare).
- Spiderant Countess - Generally not a killer for this build but all her attacks are corrosive so in the event that she does land a killing blow you'll get a Flesh Melter stack. Her attack command is extremely useful even for non-pet builds and can be used to move her around, draw aggro and even strip weaker enemies' shields.
These are the ones which I generally feel are the most important for this build.
- Corrosive Damage - This build only uses corrosive weapons so this is a no-brainer. Plus you won't always have Flesh Melter stacks so it's nice to have this as something of a safety net.
- Magazine Size - This is one of the best stat rolls in the game period and will greatly help any non-COV gun.
- [Weapon Type] Damage - V2 damage is always good (except on BOTD) and weapon type bonuses are V2 so they're good.
- Splash Damage Radius - This has amazing synergy with Hollow Point which with Fade Away and Megavore you'll proc quite often. Also helpful for taking out Buddy Systems with your pet.
- Splash Damage - This is multiplicative with all of FL4K's damage bonuses and applies to almost every weapon in this build but when combined with the already very powerful splash anoint it doesn't do much; however if you don't have access to the splash anoint then this is really good.
Any modifier combination of your choice is fine but avoid Acid Reign and Dazed and Infused at all costs. This build uses almost exclusively corrosive damage so corrosion-immune enemies are naturally the worst thing for it.
Use Fade Away as much as possible; this is especially good for having amp damage ready. When not in Fade Away, use the Reflux to proc Head Count (and also kill enemies). Against singular enemies (especially beefier ones) the Gargoyle and Ghast Call are better choices; if attacking and Fade aren't viable options then run away and let Topped Off bring Fade back for you. Also note that before you use your Fade shots it's often a good idea to send your pet after your target so that they'll activate Not My Circus faster and in the event you go down they'll be right there to revive you. The Countess is great for this because she'll get there faster thus saving you precious Fade Away and Power Inside time.