The Advent deliverance engine is impossible to defeat. Just as the super weapons were in the first Sins game, the super weapons are freaking broken. I haven't had a chance to play with or against the Novalith cannon yet so I can't comment much on that, but have heard it's pretty ridiculously overpowered as well, one shotting planets left and right. Anyways back to the deliverance engine. 

The problem: From what I have seen so far it is mostly the conversion ability of the engine that is overpowered. I was playing a game against the hard AI on one of the 1v1 maps and they attacked my home world. They wiped out my defenses but had taken a good amount of damage from them. My fleet finally got back from a few planets away and when they got there I figured it might be a little closer but between actively replacing ships via my light factory and my sizable fleet, I would be able to fight them off for sure. Then I look at my fleet because almost all of my garda's were enemy ships now and a few of my missile cruisers (Javelis). I guess the engine fired again because even more of my ships turned on me. It was a fairly close fight before, after losing my garda's I was hosed (I had 25 and they had a gazillion fighters from like 40 aria drone hosts). After losing even more, I had no shot at winning. I have heard other posts of people saying that because the AI spammed deliverance engines they are losing fleets with up to 1200 supply at a time to the conversion shots while trying to invade another star system. Quite frankly, beating this is literally impossible. It is my understanding that with the steam release (the one I am playing) the Advent have been added for the first time. It's certainly understandable that there are going to be some balancing issues. I just want to say before getting into my idea to balance this, that I love this game. In my opinion this is the best RTS game that has come out in the past 5 years at least. The advent unit models look amazing as do the other factions. I absolutely love the new UI and the design of the whole game in general, it is fantastic!!! Now on to the fix. 

How to fix it: I'm not sure exactly how to balance the deliverance engine 100% but I think that the biggest problem with it is there is no counter. With the Novalith cannon, you can at least counter it by using planetary shields so it can't one shot your planets one by one. With the deliverance engine, you just sit there and cry as all your previous ships abandon you to become a bunch of hippy dippy psi fighters for the dumb unity. Anyways, a way to balance out this ability is to make it so it will only work if the advent culture is dominant ( or at least over 50%). So for example in my case, I had a broadcast center on my home world and my culture was dominant. I think it would be fine if the deliverance engine other abilities work (perhaps they are less effective), but the conversion ability will not work. It only works if advent culture is over 50% on that planet (or dominant, this would require testing to make sure this doesn't nerf it too much). This would turn that ability into more of a defensive weapon, however it can be used offensively to dominate the enemy if the advent spams broadcast centers, dominates the culture of that planet, and then can basically steamroll the fleet there. This however also allows for defenders to counter this extremely powerful ability by keeping on top of culture. This would work in the reverse as well. In the case I read about of the guy losing a fleet worth 1200 supply every time he tried to attack the advent system (it was a separate star), if he can get his culture dominant in at least one of the advent planets, they can establish a beachhead. This makes the advent conversion ability still highly usable, but also counterable as well. This balance would also fit into the theme that the advent convert populations via cutlure and good old fashion mind control. Only when their culture is already strong, can they convert ships in the gravity well. Additionally I think it would be cool if the other engine abilities were mitigated by factors of the target planet such as research points into culture resistance as well as having opposing culture being dominant. 

P.S. just make it an option to turn off super weapons. There is a reason most people turned them off in the first game and rebellion. I think that balancing them would make them much more fun and lead to a lot less people turning them off in this new chapter of the Sins saga but having them able to be turned off would be a good fix as well if they can't be balanced well. Also it just gives people more options to play the game the way they think it is fun. Thank for making a good sequel rather than trying to capture the MOBA crowd and making a dumpster fire instead!!