Master of Orion II: Battle at Antares/Doom star design

Dreadnought: the Ultimate Weapon

 * Main Weapons: Stellar Converter
 * Special Systems: Battle Pods, Time Warp Facilitator, Phasing Cloak
 * Optional Systems: Automated Repair Unit, Achilles Targeting Unit, Damper Field, Structural Analyzer, Warp Dissipator

Strategy
During the very late end-game, if you've survived long enough and have completely maxed out the tech tree (you're Psilons who researched it, Darloks who stole it, or Humans who traded for it) you can make "The Ultimate Weapon" by combining the Phasing Cloak and Time Warp Facilitator. Phasing Cloak renders a ship not only invisible, but literally untouchable, until it has fired and dropped the cloak. The Phasing Cloak will only turn back on if you spend "one turn" without firing any weapons. Time Warp Facilitator gives you two turns in a row. Basically, if you spend one turn firing and then avoid firing at all on the extra turn granted by the TWF, your ships will recloak: you will be able to fire then recloak before the enemy fleet has the ability to return fire at all. (in patch 1.31 and above, the time warp does not give you two consecutive turns. On the first turn, do not fire, and cloak.  The enemy will then move.  Then you get two turns in a row.)

Normally, Phasing Cloaks have a 10 turn limit until they decloak, but because you are decloaking then recloaking during combat, this doesn't happen and thus you can keep doing this indefinitely. ("Fixed" in patch 1.40 and above, but 10 turns is more than enough anyways...) Theoretically, any ship fitted with the Time Warp Facilitator/Phasing Cloak combination can win the battle, so long as its weapons do at least some damage to a target (if you only do 1% damage, it will take 100 turns but you can beat even an Antaran ship; however if the amount of damage you do per turn is less than the enemy's on-board repair systems fix each turn, it's not worth it). An un-miniaturized stellar converter does not deal as much damage per space point as other weapons, such as the mauler or disrupter, especially since high energy focus does not work on the stellar converter.

It takes a lot of miniaturization research, but eventually you can fit many more special systems onto the ship which drastically improve its performance: Battle Pods of course provide more space, but this ship will have to be a Doom Star (unless you've achieved near-godlike miniaturization levels at turn 3,000 or so – which does happen in long games). In case your ship ever does end up taking a hit, add in a Damper Field and Automated Repair Unit, which, coupled with the Xentronium Armor you should have by this point (either from Orion, scrapping Antaran ships, or stealing it), will make your ship able to shrug off multiple Stellar Converter blasts. For offense, the combined effects of the Achilles Targeting Unit and Structural Analyzer with your Stellar Converter should destroy most anything thrown at you. Because Stellar Converters are a special weapon, not a beam weapon, battle computers and other beam weapon bonus systems are unnecessary wastes of space.

With increasing advances in miniaturization, you can even add in multiple Stellar Converters; there are only eight weapons "slots" though. Don't simply add in "8 Stellar Converters"; put in eight individual Stellar converters; otherwise all eight fire as one weapon. This will either waste all eight shots on one puny frigate, or, if you're firing at a planet and just want to destroy the ground batteries so your troops can invade, you'll end up killing everyone on the entire planet and destroying the colony. (As always, be careful when firing Stellar Converters at planets that you want to capture, not destroy.)

How to use the Dreadnought
The dreadnought is most effective against enemy computer AI, not humans, because the AI is dumb enough to lump all of its ships into one massive fleet. It starts out very fun when you've been sitting on the sidelines for a thousand turns, then the Sakkra finally try to invade with a massive fleet of 500+ battleships, titans, and doom stars… facing just four of your ships. The AI is often too stupid to retreat until it is numerically outnumbered, so it'll keep fighting; a human would retreat once they realized the battle was unwinnable. Sometimes the AI does realize the battle can't be won, so make sure you have at least one ship equipped with a Warp Dissipator to prevent them from retreating; you could end up destroying the entire fleet of a galaxy-spanning enemy empire, in a single battle.

Coupled with Stargates that allow instant one turn travel between any of your colonies, a small fleet of Dreadnoughts can be concentrated anywhere very quickly. A human playing against another human should be smart enough to not lump all of his ships into one massive fleet, but divide it into many smaller fleets that are timed so that they arrive in each of the Dreadnought player's systems on exactly the same turn, as even a difference of one turn is enough for a ship to travel to another colony via Stargate. The idea is that hopefully, the enemy doesn't have as many ships as he has systems: if he has four Dreadnoughts, but colonies in eight star systems, you should be able to do damage to the half that he can't cover.

Dreadnoughts are simply unstoppable when on the offensive: the best trick, combined with the above, is to send a cloaked fleet of them straight at the enemy's capital when they're brand new (thus the enemy doesn't know you have them); the enemy will send their entire fleet to protect their homeworld, and you can destroy them in one fell swoop.

Counter-strategies
Although bearing the monicker "the Ultimate Weapon", there are several counter-strategies to such a ship. For starters, it's really an offensive weapon, not a defensive weapon. Often, if you're playing as the Psilons, you'll only be able to build one, maybe four dreadnoughts (each with a Leader). Another race may have expanded to conquer much of the rest of the map, Sakkra for example, who will then try to defeat you through sheer weight of numbers.

The problem with the dreadnought is when you are on the defense: as stated above, if a player using Dreadnoughts has as many colonies as they do dreadnoughts (if they have four colonies they have at least four dreadnoughts) they've got full coverage; try to divide your forces enough that they can take out the unguarded colonies by attacking all of them at once (keep in mind that any fleet sent against a Dreadnought-guarded planet is doomed, but it's being sacrificed so the other fleets have a chance. The question is, if you're dividing your fleet between eight systems, will 1/8 of your total fleet be enough to get past the planetary defenses like the Star Fortress and Stellar Converter).

The "counter-strategy" to the Dreadnought problem is this: ignore the Dreadnought. Unfortunately, it is basically impossible to invade new planets that are defended by Dreadnoughts, but its actually kind of easy to destroy them. Simply fire all of your weapons at the planet and don't stop until it's completely destroyed, then retreat if you can. Repeat this until you've destroyed most of the Dreadnought player's planets, and they've run out of command points to sustain a large fleet… or until they're extinct.

A Dreadnought player could try to counter this by de-cloaking and using the Damper Field-equipped Dreadnoughts to soak up some damage; this might fool an AI player, but a human should be smart enough to just always fire at the planet and avoid the Dreadnoughts. The loss of a Dreadnought is nothing compared to the loss of a planet.

A final warning is that you shouldn't get too over-confident with Dreadnoughts and stop recloaking, and using your second TWF turn to fire again; enemy ships can board your Dreadnoughts if they're decloaked.

Here lies a bigger problem: Time Warp Facilitators don't work if the enemy also has a Time Warp Facilitator; apparently they cancel each other out. If the computer AI is smart enough to send the captured Dreadnought into battle leading fleets of hundreds, but never decloak it so it couldn't be destroyed, the Time Warp Facilitator/Phasing Clock trick was effectively nullified, so long as that captured Dreadnought remained. Your entire empire, which may be spread over eight star systems and be hundreds of turns ahead of the computer on the tech tree, can be completely overwhelmed through their sheer brute numbers (they can control the entire rest of the galaxy and churn out dozens of ships a turn). Eventually, you may be able to destroy the captured Dreadnought, but you'll likely be left with only one colony and only one remaining Dreadnought. It takes a long time, but nonetheless using smarter tactics (never using the second turn to fire but always recloaking) you'll be able to reconquer your empire in a long and grueling war, then re-arm with even more dreadnoughts than before, and burn the enemy to cinders; but it will take hundreds more turns to recover from this simple mistake.