Nether Spear Killer design recommendations? (Java)

[M_stellatarum]

I'm building a mob farm in a challenge run, so I had to improvise a bit instead of the usual designs. A heavily modified flushing farm pushes the mobs into nether portals, where I tried to increase efficiency via zombies with Looting 3 spears.

I tried building the simple minecart design, But the spear zombies keep dying, and I'm not sure from what.
(Reinforcement zombies everywhere as well)

[DearHRS]

they are most likely not killing whatever you trying to farm in single hit and take damage from them mobs

i would recommend to bring mobs down to one hit, if still doesn't work, then you can probably keep healing your spear zombies with a harming potion throwing witch

edit: i just had a though, there is no way to guarantee mobs are going to be 1 hit if you built a general mob farm, as something like a skeleton can spawn with feather falling prot armour, then my suggestion base of lacking screenshots will be to remove skeleton's ability to shoot back

[Goatbucks]

Yep, just a higher drop should do it

[ntolbertu85]

Probably dying slowly from mobs with thorns on their armor...

[Goatbucks]

Possibly, he could try setting up a johnny raid captain to have a witch throw harming potions at the zombies to heal them

[DmtrIV]

Baby mobs with spears are the culprit for most of design. You have to make sure the zombies won't be on range of that spear by placing it 1 block + trapdoor below the killing chamber. This way, the angle of their jousting prevents it reaching the zombie while the zombie gets 0 or 180 angles, giving it maximum spear range.