It’s well established that when Kerrigan is paired with Abathur, both of their Nydus Worms turn into Omega Worms, even when Abathur constructs them.
Is the same applied to Abathur and Zagara’s Creep Tumors? Do they get the bonus range and creep speed from Kerrigan’s Malignant Creep? Or do they remain as basic Creep Tumors?
Just to clarify: I know that the creep itself, regardless of who made it, applies the buffs from Malignant Creep. I’m looking at whether or not the Tumors are granted the Malignant Creep attribute.
From memory, I don’t believe I’ve ever observed the creep moving faster or slower between Abby and Zagara.
As you already indicated, Malignant Tumor bonuses do apply to creep between Kerri and zerg COs.
Although I am confused on why you think the spread is faster because there is no talent bonus that improves them for Abby or Zagara? And Toxic Nest is entirely different than Creep Tumor, with the only shared attribute being both generate creep.
The only instance I know of for the tumor’s change is Kerri P1, where it’s sight range is increased by +3 to 13, whereas its spread range increased by +6 to 16. The spread rate of the creep itself is decreased to 1/3 to 0.15sec versus 1/2 to 0.225sec in Malignant Creep versus normal of 0.45sec. And the bonus to units on creep goes from a plain 30% movement bonus to +30% attack speed and +1regen to +60% attack speed and +2regen respectively.
Now if you put Kerri and another zerg CO together. All creep will have Kerri’s creep bonus (be it P1 or non-P1). I would hazard a very educated guess that Creep Tumor won’t have the +3 sight and +6 spread (ie. Kerri + Zagara) because it is not a shared structure like Nydus. Think of it as “each CO has a set of unique buffs to various units and structures”, aka talents. As such, it makes little sense to have Kerri’s talent buff to be applied to Zagara/Abby’s unit/structure. However, in the instances of shared structure, we observe this. As such, we see it in “Creep” and “Nydus”.
The reason for this is because of Kerrigan’s Omega Worms talent. All allied Nydus Worms, both hers and Abathur’s, are transformed into Omega Worms. Was curious if the same applied with Kerrigan’s Malignant Creep talent.
To quote the ability: “All friendly ground units gain increased attack speed (by 30%) and life regeneration (by 1HP/s for Zerg Units) while on creep. Creep tumors spread creep faster and farther.”
I explained my view on it, did you read it? Creep tumor is not a shared structure while Nydus is.
The map editor isn’t very obvious about the details, but what I could get from it, is that the Omega update modify ALL worms-related buttons and abilities, even those that don’t exist (this Zagara Summon Nydus Worm sounded cool 
), probably affect Amon worms too.
On the other end, the creep seems to be a “passive” effect, and a validator involved seems to check if the “casting player” got the upgrade to apply it, not if “the upgrade is enabled for the game”, so I would suppose it’s not shared.
But maybe I followed the wrong links in the editor, and there’s more to it, or I just misunderstood what I found.
Alright, thanks for the answers guys.
yeah, the editor has a specific part in it that details shared upgrades between allied players (Kerrigan’s Omega Worm being a prime example). Malignant creep is complicated due to how it’s implemented, but as far as I know, the boosted spread from tumors is not shared between Kerrigan and her ally