Meh. The cards under him end game timer smells too much of Blade for my tastes, and, while having a nice ouroboros feel to it (if Greatlactus is the end game villain) I expect it to be more than that, something we haven't seen before.
What I would like (and this is of course wild specualtion or it wouldn't be in this part of the forum) is a villain that has no HP and is defeated by sacrificing part of your deck somehow, the ultimate expression of heroism is sacrificing yourself afterall.
I honestly don't think the big cosmic villain is going to be in WotC - I think it'll be in the final set. I think WotC is going to be build-up to that, giving us a glimpse of the worlds and realms beyond the Earth of Sentinels.
There are pleanty of things in the Sentinels Universe that are "forces of nature" but are still targets. Just cause it's a "force of nature" doesn't meant mankind doesn't need to be protected from it.
As for saving the Galactus villain for the last set, yeah, I see how that makes sense, but he would fit really well with this theme. If he were to be in the last expansion too, it would pretty much have to be another space based one, which seems a little redundant.
Since I agree that the Galactus villain should be saved, make a silver surfer/herald type character. Still fits theme, fits the timeline and builds up the story in preparation for the "final battle". Although from what we've heard from tactics I'm starting to think the final act of the story is going to be more super v super than super v world ender of doom and despair and being mean.
Also I know the silver surfer is a hero, so I give Terrax as another herald who isn't a good guy
Its about perspective. It can be a villain in the game without being a "villain". The Dreamer, by all technicallity, is a hero.
And I'm not sure how I would feel about having a herald in the game along with a galactus villain. It seems a little too on the nose as a straight up copy of it. But, if there was a herald, I feel like it would be part of the not-galactus deck instead of its own thing. Maybe like a second character card, like with Kismet, and there could be ways of making him be a good guy and help. Or maybe the herald is one side of villain character card and not-galactus is the other side.
This is all speculation on speculation at his point though. For all we know, the 4th villain could actually be an army of tribbles.