...well this is Djinn-bait if I ever saw it. And I have. Here. I love it and, as a designer myself, feel I should preface with that before I start to critique. That said, let's dive in. I'll start with just Treeline, as I've got a lot to say on all of these. :D
#TWISTED TREELINE
Introduction: You lose a lot here by not identifying your up-front goals and areas of noted opportunities improvement. By not doing this you're forcing the viewer to not only guess at the problems you identify but also at the validity of the solutions you propose towards resolving those issues.
Ebonmaw / Vilemaw: This is a good example of the above. The question "does Twisted Treeline need more early objectives" is a good one, but assuming that the difficulty of snagging an early game Vilemaw and that the altars don't sufficiently fill the early game objective role seems ill conceived. Is using the Vilemaw design space the best use of this, or might it be more interesting to increase the push/pull of the altar game or include additional power boosts that could be used to secure that early Vilemaw? The Ebonmaw proposal isn't bad, certainly (although the fact that it boosts your HIGHEST stat -- which may not necessarily be what you WANT boosted -- is frustrating, especially as in non-coordinated teams there will be fighting over this in a way that isn't shared with Rift Herald, which helps the entire team), but I feel there's analysis missing on why you picked this options.
Altars: These feel a bit more skewed than the current buffs, and not in a great way. Homeguard (on a map this small) largely removes the penalty for being forced out of lane, which is a great way to secure an advantage when this buff doesn't exist. This leads to an easy win-more, as it's reasonable to retreat out of an altar fight, heal, trigger homeguard, and rush back to defend it. On top of superior sustain AND superior harass if you have all altars, this makes that advantage potentially overwhelming. Additionally, while the ally buff effect is intriguing, this has two effects -- the "who gets it" potential fights that the Dragon buff suggested above has, and a loss of the ability to deny / contest the current relic, as you've team-locked the individual buffs. This leads to a win-more effect that exacerbates the strong altar bonuses you've already assigned.
Assorted: Your sweeper changes are great, and the jungle suggestions are solid -- although I suspect that using Raptors or Krugs would actually drastically change who can jungle in Treeline, as those are two of the more brutal camps that kind of dictate who can and can't jungle. I suspect you'd see a reduction in viable Treeline junglers, and would, as a result, suggest that perhaps other changes would be preferable.
Promotional: The promotional ideas are on-point, especially the Arcane Sweeper effects. That's a great little spot to add some flair without impacting the game hugely. Pool Party I think doesn't make as strong a case for itself, as Treeline would need to earn that level of attention through an increased playerbase.
Team: I think a big failure point here is that you don't make a good argument for WHY Treeline (or other modes I haven't gotten to yet) merit this level of dedicated resources. Every developer or artist or designer you put onto Treeline for any length of time means a developer, artist, or designer not working on other gamemodes that have proven to be more popular -- this is true to such an extent that even on ARAM (a rather popular mode) champion balance is done in broad, sweeping strokes of +- % damage taken/dealt. While that might be viable on treeline, would it be sufficient, in your eyes, if that were the primary means of balancing champions? If not, what would your suggestion be for sufficiently reducing the production needs of fully supporting Treeline as a first-class game mode?
