Acid/poison PBlades. P stands for poisonous, totally badass and also makes sense to throw such knives as rogue type of character.
Other than that another vote for no CD Aegis. Even just for the pleasent metallic sound of it’s attack, perfectly combined with breaking a vase sound effect of activating Guardians of Empyrion.
Also some additional help/mods for Acid Drain Essence? FX for Fire Totems is also dope idea, I agree with previous comments.
While I love memes, hopefully the price of conduits will be reduced since adding prefixes will make it harder to get the one you’re looking for.
That being said, Baldir’s set supports bleed damage and demo skills, so we desperately need a bleed demo conduit. So my vote goes to Bleed Grenado. And maybe % bleed on Flame Touched 
Let the age of Bleed Commando/Shieldbreaker/Saboteur/Pyromancer begin 
Chaos Trozan Sky Shards,
there is basically no itemization to actually support the skill points, but the FX is gorgeous (already exist in game), wont be OP, and i want it
Pierce AAR
it’s currently possible to sling a partial converted pierce AAR together, but the lack of Aether conversion makes it kinda meh. Also since the Treacherous means belt was moved to gunner means Spellbreaker version is basically bleh, having to use the conversion gun
(Re)move Frenetic Throw conversion to open up spam PB memes
Aether/Chaos Forcewave
Pierce Wind Devils/Storm Totems
pierce pets trickster kinda sucks, losing all the dot, but maybe it can be made ok?
Acid Blade Spirits on acid wind devil conduit
alternative on a non-conduit conflicting item that can be paired with Acid Wind Devil Conduit 
Pierce Vines,
thematically vines entangling and “thorning” you seems like a natural pierce attack, could add 1%WD to vines to allow for regular pierce conversion
Chaos Stormbox/Chaos Rune of Hagarrand
currently ele->chaos conversion is pretty tough to get high globally unless slapping 2piece voidsoul on everything, maybe a direct mod/transmuter to these skills would allow for more fun
+points isn’t super easy for either, so i doubt it would enter OP territory
Piercing Pets conversion
none of the pet masteries really support pierce RR so probably wont be too absurd, meanwhile it sorta “fits” thematically with Briar and Primal Spirit, Skeleton Archers
Request to please expand Doom Bolt/Lightning Bolt proc affix pool
Earthsplitter changed to 100% Pierce->Phys conversion
The Adversary modifier
making the projectile become lobbed grenades when it shoots/is used for ranged attacks
Poop bonus, need more fecal jokes,
maybe make the various feces items part of a set with a turd bonus?
I haven’t created the build to test it out, but Acid PBlades looks completely doable; 2 sec cooldown with the fat weapon damage and 22/12 Lethal Assault looks like it could be more than a meme, but a passable option.
I’ve worked with Acid Drain Essence in the past; but I’ve never been able to get it past SR65 due to how much of an energy sink it is. Even with as minimal interruptions as possible, Acid Drain Essence doesn’t have the oomph to beat out enemies before they hit you for substantial damage.
I’ve poked around with it too on an Infiltrator and just like yours it is untested. Running numbers on it though, the shotgun on PBlades should be exceptionally strong. Only major issue would be energy management on filler skills between nukes.
Even if it’s technically doable, having some item support to lessen the need for stacking itty bitty pieces of Pierce/Chaos/Cold conversion (Vitality is easy) would open up more options in those item slots to experiment with. Not outlandish for established builds or playstyles to receive conversion modifiers or item sets like Pyran for vanilla Meteor Sorcerer, not that I’m suggesting an item set for Acid PBlades here, just pointing it out as an example.
I still hope to see spammable forcewave with shield.
Something similar to Frenetic throw and Spite’s granted modifier.
Probably it will not quite clear, if conduit add modifier to shields wielding only, because shields have about half WD compare to 2H and penalty balanced around shield could be not enough for 2H.
On the other hand, shield grand more defence and lower damage is logically compensate it.
Random thought to everyone in favour of spammable shield Forcewave: what about removing the cooldown on Hyrian’s Claw and making it spammable? 
. Similar kind of item to Stormrend or Spellscourge Bulwark, only downside is Physical Forcewave with it gets shafted having to deal with the Physical->Elemental conversion.
more ragdoll !
not just in general,
but maybe like a 2h Cadence/Forcewave modifier that lets you either ignore gibbing so ragdoll is guaranteed
and lets you ragdoll bosses sending them flying across the screen !!!
I will never oppose buffs to hyran’s claw
What about acid conversion for Phantasmal Blades with a bit of retaliation added to attack? Nightblade already has retaliation support in Merciless Repertoire and Blade Barrier lol.
It would also be a nice alternative/complement to retal DEE / Righteous fervor and we would see more Mythical Dreegal’anore around.
I thought the exact thing after reading previous comment. That purple Forcewave looks gorgeous and i would like it to be spammable.
I’m getting strong extra cooldown Aegis of Menhir vibes here…
Get outta here you cheeky fuck 
Extra cooldown Aegis, but you can use 2 handed weapons for throwing.
+1 on no CD Aegis, the elemental aegis conduit can just be replaced (since all the supporting gear is fire anyway) or moved to the Hyrian shield so it finally has identity and a use, that’s perfect
Gutripper modifier
that allows Blade Arc to be used with that rifle, either melee hit or alternatively turn the projectile into the spinning blade FX ala vendetta relic etc
Boner Bois Bombs,
change skeleton conduit or bound wraith to make skeletons get the suicide bomb upgrade on death, aether dmg 'splosion mushroom cloud 
Callidor’s Acid Reflux,
converts all Callidor’s Tempest dmg to Acid; but turns it to a spam attacking buff so you can use other skills while it still “procs” couple times a second around you automatically
Piercing Mortar Trap,
that also changes Big One to add Cluster Bombs/Canister Bomb effect/frags on impact
Cold Mortar Trap,
alters Big One into Trozan Sky Shards
Piercing Pierce Doom Bolt
changes the Doom Bolt to be applied horizontally - could plop it on Jarinthor’s Head 
Gaze of Empyrion helm; modifier that changes Guardians of Empyrion’s cleave attack into Sun Spot
Spectral Bolt,
but good/high dmg version, so granted by high level item, idono like VoS maybe?
Shotgun ABB
Venomlance/Quillthrower adds 2 projectiles to ranged ABB for a 3 round shotgun ABB burst
Blade Barrier modifier;
removes dmg absorb and immobility, but adds duration and reflect, turning it into like temp retal buff
Wendigo Totem transmuter:
turns it into a tiny little wendigo that runs around (on a short leash range) and lifetaps to you
Bullet Mosquito/Condensed Devouring Swarm,
increases Swarm dmg, but reduces the aoe to a regular “chonky” projectile - no idea which gun to put it on tho
okay maybe that last one was a little less serious 
(or was it ?)
Forgot to ask, something like this would be fantastic for Mirror of Ereoctes as well.
Imagine dropping Mythical Avatar of Order and Mythical Turrion’s Reprisal onto an Arcanist, then having the following alterations:
Some of the Fire/Elemental and % Retaliation damage on Turrion’s Reprisal/Avatar of Order’s modifiers will need to be cut down as well but regardless - opening up Arcanist as more of a valid option for Retaliation would be fantastic to see, even if it’s just supporting with some nice stats and passive damage to a more primary skill provider like Demolitionist or Oathkeeper .
As somebody else pointed out, some of these pierce ideas are technically possibly now, but having the bulk of the conversion tied to Messenger’s Repeater makes it real clunky.
Also, +1 for aether mortars and fire totems. That would be neat.
Last I checked single RR vitality is still considered a meme, so could cadence get a skill mod for it/full conversion support outside of Edge of Death? Actually has a decent amount of +skill gear support scattered about but no way to get full conversion unless you use that sword. I want to do a dumb vit cadence gunner with Bysmiel Handcannon - Items - Grim Dawn Item Database but capping at 68% conversion seems like a non-starter.
I’ve never seen anyone use the Mirror of Ereoctes bonuses on Crown of the Revenant King, or really anyone other that vit oppressor gunner use it in general, so maybe those could be swapped for a cadence/soldier phys to vit conversion mod? More meme level Warlord and Death Knight options should open up with it.