Not enough caffeine for my first posts/replies so I wanted to clarify a couple things. First, each raid engine spawns a single Dreadnought per tick, for a total of 2 per double-engine wave. (TBH we had 4 up on a large percentage of our attempts owing to the timing with killing the second engine).
Second, I didn't mean to say that a Dreadnought isn't still scary in it's own right. Ditto with 500+ core mark ships. Either of those would still be brutal to deal with, but comparatively to a combination of 2 Dreadnoughts and 1000+ core mark ships that caused the massive headache, they are "deal-able."
To keith, if you're interested how we dealt with the pair of core raid engines with the dreadnoughts, here's a quick rundown:
The layout was this: My Highly Defended World (the real world we want to fight them at) ---> Mk3 World (our bait) ---> Core Mk IV ---> Core Homeworld (With 2 Core Raid Engines).
I took the Mk 3 as a fake world for the raid engine waves to hit first. It had a Factory IV, but we had one elsewhere from way earlier. Perfect bait. Knowing the AI prioritizes targets like that, I put dozens of mines in a line between the wormholes from the mkIV and to my real world. Loads of sniper turrets at the ends. Not that these will do that much damage, but they were just to buy us some time between the spawn and having to fight the 'noughts.
Then we took a couple extra worlds with high mk spire asteroids. From these we built a couple dozen mk3 and mk4 rams, four mk 4 atritioners, and four mk4 martyrs. We hid those at a world adjacent to the world where we really wanted to fight.
From there I had Brisebonbons bring about 75% of his fleet over to the real battleground world.
I built a full cap of transports. Loaded 75% of my ships in those. 1200 mixed ships total. About 100 ships per transport with about 7-8 dummy transports that were empty. This sounds weird, but what we realized after a whole bunch of other failed attempts, the only way to beat this was to skip through the core mk4, into the Core Home, and straight to the first raid engine and get enough ships there to pop it (only 6 mil hp) and then have enough transports left to re-load 200-300 ships and cross the map to the other and pop it. Any ships that got stranded would just serve as a distraction to give the strike force space to frantically do it's thing.
This meant we had 4 minutes from crossing in to the core mk 4 to kill both. It was ugly, and I lost the full cap of transports and all 1200 ships but got the second engine with 15 seconds to spare. Couldn't have done it without abusing the transports, I think.
So that left us dealing with the wave. The bait world bought us about 2 minutes while the dreadnoughts and ships wandered around and evaporated anything there, with the mkV ships eating many many mines along the way.
At this point, I've managed to rebuild about 50% of my fleet at a nearby world and the light show starts: We use the attritioners, placed deep to the side in the backfield of the defended world to lure away the core ships, which are then, SURPRISE, all grabbed from behind by the martyrs that pop through the wormhole behind them. That kills about 600-700 of the ships. (Note: Brise kept his ships in transports until the AI fleet started moving.)
(This happened almost simultaneously with the atritioner/martyr trick:) Though in reality, we really just wanted the core mk death ball to move away from the Dreadnoughts — Pulling a move from the Zap Branagin playbook, we clog it's cannons with our ships to distract them. During the slaughter, I take 20+ spire rams and pop them through from the next world over and plow in to the Dreadnoughts with only seconds for them to react. Boom.
It was a giant mess, and we probably lost about 3000 mixed ships total, but hey, that was the hard part! And we only lost the one world we had planned to lose!
*Edit* I realized that many of you might be going, "Why no golems?" Well, because of course this is the game Brisebonbons and I were experimenting with game settings and have them completely turned off... So golems weren't an option.