Offensive Vasari starbasing is very annoying.  The way to stop it is to keep scouts on the lookout so you see the migrator coming before it arrives.  Migrators are quite fragile and it's usually quite easy to kill them before they arrive, or at very least get units in position to destroy the starbase as it builds.  The problem is this usually forces you to play very defensively and keep lots of units on standby... just to counter the threat of a single migrator! 

Now, it is beatable.  I played a game against Waxworks yesterday where he was constantly trying to do this to me, and he only once got a starbase operational (I blew it up shortly afterwards by rushing it with destras and disciples before it could upgrade.  However, if he gets a starbase operational with all upgrades... in the early game that means he owns the planet.  You can try to chip it away with bombers, but if he's got backup or invests in a hangar upgrade that won't work.

The alternative is to instead put all your money into fleet and push on the enemy.  A single well-upgraded starbase costs about as much as 30 or so frigates, and early-on that's enough to tilt an early battle well in your favour and really rip up his empire. 

If you only have one hull and one weapon upgrade, a starbase can be easily beaten by rushing it with units.  Heck, just pelt it with bombers while constantly moving away.  Such unupgraded starbases are pretty easy to take down.

Personally, I never leave starbases unupgraded.  There are lots of capital ships that can solo an unupgraded (or even lightly upgraded) starbase, and I simply don't find them worthwhile unless you plan to turn them into real fortresses with repair platforms and some fleet support.  The idea is to lock down key locations to hamper enemy movement and block their advances and retreats.  You may sacrifice a lot of fleet to do this, but if you play the position well it can be extremely effective.

Anyways, the point is that someone who invests in starbases is going to have a reduced fleet level.  Sometimes this is a great tradeoff, sometimes it's a horrible one, but starbases add a lot of option to the game.  Without them, you have virtually no defensive recourse and the game is all about fleet power.

Very few people fully upgrade starbases.  Usually I put 3-4 on my starbases and leave it at that.  The first few upgrades drastically increase the starbase's potential.  A single hull upgrade more than doubles its durability, a single weapons upgrade doubles its damage output... so a single hull and weapons upgrade basically increases this thing's combat power by a factor of four, but only costs a factor of two.  Beyond that, though, you get diminishing returns, which is why most people stop around 4.  It doesn't make sense past that point to throw more eggs into one basket.

As for investing in a single gravity well, remember that starbases can impact events outside of their range of influence.  The most obvious effect is it prevents enemies from pursuing retreating units once they reach the starbase's influence, but more importantly it prevents enemies from passing through the gravity well, blocking both attack and retreat paths, while giving your own forces fair use of these routes.  This can enable you to outmaneuver an enemy if you place the starbase at a critical junction.  It doesn't stop the enemy from running past a starbase, but losing all your antimatter and 20% of your hull points is a pretty big deal if your own forces are nearby to punish them for this.

That would be best.  One thing you can do to make it even more effective is to set your bombers to "hold ground" mode and just give them an order to move next to the starbase.  They will sit there and attack it like a regular frigate (but it still can't attack them back) without any of their usual attack run behavior, and this usually results in higher overall damage output.  Just make sure to set them back to normal move behavior afterwards.

By the way, the best way to counter someone who is doing this with bombers is to do the same thing, only with fighters.  Park them right next to those stationary bombers and watch them fry.

While advent starbase is nice, it is very difficult to use offensively especially against vasari.  The build speed is just too slow and vasari are better at taking out single targets than advent anyways.  Plus they can always build and upgrade their own SB in the well faster than the attacker and there is no moving away for advent.  It is generally not the best thing to use defensively against a vasari SB because again.....it can move away and regenerate.  If you can really hole up with it with repairs and hangars with shield bestowal then they really can't do much until they get rid of the hangars.  You can hold it back pretty much indefinitely until they do get rid of the hangars with shield bestowal if no/little fleet comes with it. 

The answer to vasari SB is closer to what darvin said.  Bombers are best if little to no fighter presence.  Barring that destras are the next best answer with a few guardians using their shield ability and a progen to restore.  If he is rushing SB early, disciples are preferable over illuminators unless he has a decent amount of kanrak around.  Illuminators seem like the better choice but they are not.  Illums have 17 base damage half of which,8 and some change, is in front to hit the SB.  Disciples do 8 damage base all front, are cheaper, less supply and more cheaply upgraded.  If the enemy does have a decent amount of kanrak this will be limited because it will fairly well tear through the disciples.  Hope this was helpful.

[_]-Greyfox

Actually, I made my coup-de-grace in a 1v1 the other day with an Advent starbase on my Vasari opponent's homeworld.  Starbases are great against Vasari because they'll kill any subverters that try to shut down nearby frigates.  If you have enough forces, you can keep the phase missile units from focus firing the starbase. 

However, I completely agree that you don't use starbases as stand-alone installations against Vasari.  Always back them up with fleet and capital ships.

Normally Overseers are a great choice to protect a starbase, but not against Disciples.  Remember, disciples can steal antimatter, meaning your Overseers are drained before the Orkulus' shields have been depleted!

As far as illums versus disciples, this is a fool's choice.  Both will work in a pinch, and it's simply a matter of having the necessary quantity.  This will slant your fleet strongly to either LF or LRF based, so your choice should represent your other strategic needs at the time rather than some miniscule preference against this immediate threat.  In any case, your best picks are bombers and destras, so if those are available go for them.

You'll get better performance out of bombers.  The Adjudicator is so weak to fighters that there's really no reason to ever get it; if there aren't fighters, bombers are able to attack with impunity, and if there are fighters then the Adjudicator is equally screwed.

If you've got three hostility labs and are making disciples, there's no reason not to.  If your opponent is using an Overseer/Orkulus, you'd be quite foolish not to.  If you plan on charging the starbase, you need to incapacitate the Overseers first, and this is by far the fastest way.

I could see it working, though you'd need the battle to be taking place fairly close to a phase lane leading to a friendly planet.  Still, the disciples will negate those overseers faster than any other unit type, and once he realizes you're keeping overseers in reserve he'll start keeping some disciples in reserve.

25% is not always 25%.... the difference between 5% and 30% is not quite 25%... and the difference between 75% and 100% is 33% more damage, and the difference between 25% and 50% is 100%. (in better terms... disciples take 33% more damage from the base, and double damage from the chaos bolts that illums take)

you are right about one thing, illums are tier 3, and starbases are tier 2.  if you have illums, you should also have bombers, and if you have bombers... why are we talking about disciples vs illums. heh.

I did some tests... durring the time period when scouts/lf rushing was very popular, and I found that a vasari starbase was the most effective counter (literally, the only effective counter that cost less than the disciples and scouts)... so, i guess i could redo a few tests with illums, and see where exactly the point is where the vasari starbase just barely dies to the fleet attacking it, but that requires time and effort that I simply dont have the time for right now.

Illums never have been a SB cracking weapon(which is kinda what I have been saying).  They get eaten alive by an orkulus.

[_]-Greyfox