The Sowers Nemesis of the Vodyani and Cravers

The Vodyani leach planets, and the Cravers completely depreciate the planet, and then "nibble" on the captive populations; but why not bring back an Endless Space faction the Sowers, to be the balance against them? 

The Vodyani and to an extent the Cravers are predatory factions. So I think the Sowers a faction geared more to terraforming planets into perfect homes for minor factions. So the conflict would be the Sowers would be terraforming barren or dead planets into lush oasis in the galaxy at large, but they also have to combat a menace that not only targets their new lush worlds, but also strips existing ones clean. 

So the Sowers would be interesting to play off Cravers and Vodyani. The Cravers and Vodyani would attract Sowers attention because they would be practically destroying their planets at an alarming rate. But at the same time both Cravers and Vodyani would target Sower controlled space due to its rich and lush planets with revitalized resources and populations to exploit. 

Now the downside, as the Sowers terraform planets hostile empires can colonize a terraformed planet from under a Sowers action. But if there are alot of barren or dead worlds in systems the Sowers gain alot of control in the beginning. Also having the power to terraform from the outset of the game, can be used offensively and defensively. So Sower players can deliberately practice "Scorched Earth" or "Greened Earth" tactics to force players off their territory or create buffer zones. Besides the fact that the Sowers may have to remove those who don't want their "beneficial attentions" or defend their new lush garden systems from "pests." 

Of course, you will need to repopulate said worlds. So they would have a unique mechanic that would allow them to "redistribute" [excuse my memory is blanking on the proper word for forcibly moving people to where you want them] by forcibly for the lack of a better term abducting them, or just plain invading and collecting those annoying little organic specimens you want in your garden. 

Now Sower populations have to be built, and you can find and discover or even evolve into more efficient forms of Sower population. But the more you build Sower populations or evolve them more expensive and slowed down the terraforming process for a planet becomes. You need a certain number of Sower populations to allow for a certain type of terraforming. 1 Sower can convert a planet into 1 tier of terraforming from Barren or Dead. 2 Sower can convert a planet into 2 Tiers of terraforming from Barren or Dead, then into Tier 1 terraforming then Tier 2. So this puts a reasonable choke on suddenly jumping to whatever planet terraforming you want. The Sowers convert industry into terraforming points, then once the terraforming is done they help per Sower population additional food production. 

So the most important thing is repopulating the newly terraformed planets with pops from minor factions to increase your FIDS. Because your main drive is terraforming and defending those terraformed systems; or invading a system who so desperately needs your terraforming green thumb help [sarcasm noted]

Now Empires like the Unfallen will probably benefit greatly from interaction with the Sowers. And the sowers would probably give the Unfallen a boost in tendril speed and colonization in areas which they have terraformed. But hungry Empires like Vodyani and Cravers would eye the  newly terraformed areas with hunger, or with sheer terror because the Sowers would get a huge bonus vs. depleted and barren stripped worlds. [Hey that is my empty plate why are you refilling it when I was done!] Meaning the Sowers would have to be beaten off because their drive would be to terraform those worlds under Vodyani or Craver attentions. Wandering empires like the Vaulters might just be happy to have a planet they could easily colonize. Other empires that need certain planet types to increase their FIDS would not be happy to have their planets terraformed into something they didn't want to. 

So using Sowers terraforming mechanics you can deny access to planets or bonuses. Now in retrospect a Sower "colony" is using the materials of that planet to make other planets inhabitable. So technically there would be a downside. The sowers would have to colonize a planet to build other Sowers and then terraform in that system. But it is a choice of which planet you will use as the base for terraforming. Now you can swap to terraform that planet if you think its a better choice, but you will have to de-terraform the previous planet in order to do it. The Sower Colony, can only be inhabited by Sower pops, which can move around the galaxy freely, you can convert those pops into "colony" Sower Ships, with varying amounts of power due to the pops in that ship. 

The quest would be the Sowers having a goal to  terraform and re-populate X number of systems; but also a sentient quest of why they exist and for what reasons; and the Sowers discovering who made them and the reason for the all driving terraforming existance. 

It might make an interesting counterpoint to other empires. Where you are cultivating your empire for different reasons than just to extract, your goal is the re-populate and spread populations across the galaxy.  You are fighting to protect and expand life across the galaxy; probably to the inane protestations of those tiny organic specimens you "plant" on your newly green worlds. [Hey who wouldn't want to play a "God" faction vs the other empires?]