Advent Superweapon

They don't immediately change alliegence, they just give the target planet a massive boost to the culture rate (whether it is on your or your opponents planet). Fire it at a planet with no culture buildings to see how much (though it is effected by the number of phase lanes connected to the planet). I find it useful for firing at my front line worlds, so that my culture can reach the enemy's border worlds. If you research the tech that gives you line of sight with your culture, it can even be used as a good spying tool.

Still, I consider them the worst of the superweapons. However, in entrenchment they now give a damage bonus to your ships in the gravity well they fired on, so they have some combat use as well.

It really does need some improvement.  Maybe it could be changed to also destroy any culture structures on that planet and perhaps those at nearby planets?

Maybe it could increase culture on your planet, and spread non-culture when it hits enemy planets (i.e. red enemy phase lanes indicate culture, once advent superweapon hits, the normal grey starts spreading from the planet instead, stopping after a certain amount of time. then the phane would be culture-free. don't think replacing it with your own culture would be fair, though.)

The damage boost is also present in Vanilla Sins (+15% damage). The DE has the same effect as 5 culture stations with no upgrades.

OK, here's an interesting idea.

The Advent superweapon wouldn't destroy enemy culture centers--it would reprogram enemy culture centers at the planet that is hit and any that are connected to that gravity well, taking them over, turning them into your culture centers with your maximum culture rate spread bonus (30%).  The enemy would have to go destroy them.

I don't know, personally I really like this particular weapon.  True, it's not really intended for use beyond a support weapon, mostly granting your culture bonuses into enemy worlds that your fleet is attacking.  But you can relatively easily culture kill a planet and it's surrounding wells even when you're nowhere near to attack if you have more then one and repeatedly fire.  It takes time, but it has the advantage of being overlooked or ignored because of it's lack of immediate damage, or even impending fleet threat (as compared to the Vasari's where they may jump in).  So it can easily cause planet loss and major income hits unexpectedly to those who do underestimate it.

I find that if the enemy has no culture, or very weak culture, the Advent cannon can wreak some real havoc.  However, if the enemy has strong culture coverage and it is teched up, the cannon's culture effects are minor and are rapidly shrugged off....even when you fire a few at one time.  It does cause some economic impact and convey a culture bonus to you in that gravwell for a brief time, but against strong culture the effect is so small that I am not sure it is worth building a chain of cannons.

Considering the amount of havoc or economic impact you can cause with 2-3 TEC or Vasari superweapons, the Advent cannon seems a bit weak.  Of course, everything else about Advent kicks butt, so I'm not ready to cry for them just yet!!!

It would be interesting if instead of an offensive weapon, it was a massive defensive weapon.  It's effect on enemy planets would be unchanged from now, but if used on your own planet it would give a MASSIVE temporary alligence boost.  You could use them on key planets to kick your late game economy into overdrive; through the power of brainwashing.

+15% damage to Illum spam is underpowered??

Deliverance Engine is equal to the other weapons in terms of power, it just puts that power in another part of the game, while still making it combat-capable.  Advent are Culture/Squadron based in terms of superiority, and a superweapon that delivers squadrons to an enemy planet would be most likely useless, as it couldn't send very many (Say, a dozen at most) and they could be easily defended.  TEC has a planet assault weapon, Vasari has a Grav-Well assaults system, and Advent has an espionage system.  YOu just have to know how to use it properly, ie, a jumpstart on your own culture spread rate.  3 cannons here is plenty for that purpose if you target the first shot for each carefully, then set them to auto-fire at random.  Advent doesn't need the powerful combat superweapon, as their fleets kick ass already.

Does the 15% bonus apply to strike craft and structures?  How about to allies?

I believe so, at least to the allies part.  It is FRIENDLY culture after all.  Not sure about squadrons though.  Darvin might.

Can you imagine the use of this thing in team games if it does?   That means your econ guy can give a 15% boost to ALL team members. 

Only if they are all of their ships are in the same gravity well. That plus the time it takes for the shot to actually hit the planet, it's far from an effiecient or easy to use weapon.

I personally love the advent superwep, late in the game when I have 10+ of them I just set them on autocast and watch my enemies economies get obliterated, much more useful in the long run then straight up damage