Been searching the forums looking for it, but I've not found any info besides that the arrow deals additional damage that's also affected by Armor.
With the way it's worded, it looks like it adds a Poison that triggers every time a creep is damaged, right? So, if I use a damage over time effect, does it trigger on each instance of damage?
Example: Frog deals 100 damage on hit (20 Hydra damage) it also deals 100 Poison damage over 3 seconds (6.66~ x3 if it's once per second, I don't know how damage over time works mechanically)
Does the Hydra damage count as damage that the Frog is doing? If so, does that mean that it adds 20 more frog Poison damage over the Hydra duration? And an extra 6.66 on each tick of damage? Would Hydra keep dealing damage on those two? (4 and 1.33)
Side note, I'd expect the Hydra damage to ignore 30% armor if used by a Frog, while Solara would get the usual damage?
I expect that hydra arrow just takes initial hit dmg and scalar with that. Nothing more.
Using it on solara and frog would be a waste of inventory slots then.
I have no hard facts for that but this would be the straightforward solution. Also it would have the same dynamics as these towers have which is what you would expect here.