If your enemy has deceptive illusion, then they have 5 military labs...if they have 5 military labs, then either 1) you save a bunch of money by only having 2 or 3 mil labs and can therefore have more ships or 2) you build 5 military labs as well, and spam HCs (which are only countered by bombers and hoshikos with dem bots)...

That's one way to look at it anyway...

If you are talking more early game though, it really depends on the exact composition of forces you are going against...pretty much everyone will be doing a combination of flak + LRFs regardless of what faction they are playing, so this ilum/defender spam you speak of is the same thing that Vasari and TEC will be throwing at you...

Most people only have a problem real early game as Vasari going against the disciple/defender rush...that really should be the only matchup that is problematic....everything else, and really your goal is just to be bigger and badder than your enemy...have a better economy, and have more ships...if you are really in doubt and have absolutely no idea what to build, just mimic the force composition of your enemy....not exactly the best strategy (usually want to use counters) but if you have an advantage in numbers then you may win by attrition...

You can only counter lf, flak and lrf advent fleets with strength in numbers. Assailants are a must have but so is Flak and bombers-not fighters Gamer-lamb because fighters are torn to shreds by the defense vessel: the best flak in the game-and lets not forget how fighters will not only have to deal with flak but also push damage from halcyons should it be present.

Vasari Bombers are insanely buff so survive longer dealing more damage to desciples, defense vessels and reasonable damage to illuminators.

Titan.

Btw, if someone in beta 1 asks "how beat X?"- answer is always titan.

So.....

TITAN!

or alternatively: ditch Diplo, get Rebellion and build titan.

So... titan.

This is actually VERY easy for vasari playes to counter, they just need to build some defensive turrets(5-6) + 2 repair facilities to protect their frigate factory/labs.  You need to then build some flak after the disciples have been thinned by the turrets, and then once you have say 10 flak you should then spam pure kanraks to get the critical mass to chase that halcyon out of your gravity well.  Its the noobs that do a starbase rush on a disciple spammer then it gets popped and then they are out a lot of resources and their homeworlds are going to come under quick assault that have the most to worry about an advent disciple spam. 

It is only an uphill battle if you don't acquire enough neutrals and the advent homeworld is stationed very close.  From what i've seen in rebellion these close quarters (homeworld next to homeworld, or 1-2 jumps away) don't occur with nearly the frequency that they did in diplomacy. 

If the vasari player acquires 8-15 neutrals the advent player still will be at a disadvantage as the vasari player can then spam kanraks from their built up asteroid and save their homeworld.

An advent hw next to a vasari HW should result in the advent building some scouts to knock out vasari constructors, and the first structure the advent player should have built is a second frigate factory for immediate tier zero spam.  In this situation the vasari don't have a chance unless they have already build a colonizer capital/safety colony ship and decided to move shop elsewhere.

yeah its still an observation with a tiny amount of data, the law of large numbers hasn't been obeyed yet.