This will make every character have an equal chance at being able to take out roots, which will be easier to balance in the long run, assuming that character's attacks do near equal damage per second.
To make myself perfectly clear, when I'm talking about Armor, I mean as a mechanic throughout all attacking interactions, not just with the roots.
1: Larvae one by one. It makes more sense (what trees die just by losing one root?) plus you could potentially have roots that grow back, or some sort of morale system based on amounts of roots alive. It gives you more to expand on.
I actually like where this is going.
Another thought is that the roots could potentially have some kind of attack of their own (sunken colonies covered by the sprites at the top of the tree?).
I considered something like this but decided against it. It would create more obstruction in an already tight quartered environment. I should mention that each base will have one guardian (a Dragoon), which will serve as the bases' defense. I don't know how the Dragoon should scale/change throughout the game, however.
I agree with the above. You should make it so if after X time goes by, and there are Y remaining roots, the larvae are healed. So the other roots "heal" the damaged one. And the last root won't be able to heal itself. Healing can be done with medic, setting hp via triggers, or just instant 100% heal.
You should also make the roots heal-able by heroes (they just wait near them or something, and heal them faster/instantly).
I have complete control over the roots' healths, as we are using vHP, which brings up another question: Should the roots be damageable via spells? The plan is that they shouldn't be and I very much doubt my mind will be changed in the matter.
I like the idea of having individual roots, each of which must be killed.
This is how it we have been triggering it to be so far, though technically it'd be easier to do it with a collective health (fewer variables to keep track of). Looks like we'll continue doing it this way.
2. Harder question. The 2nd idea seems cooler and would make a change ... I say the 2nd option though.
I believe that you should use the DotA/WoW-style armor.
If popular opinion keeps leaning this way we'll make the change. I'll need to come up with a good formula for diminishing returns, then.
None.