The example I proposed was a Lazuli Pylon combined with, say, Sarkonis HQ (10% Defense Bonus).

On the Colony tab, I would show as having 0 defense. The lazuli pylon would normally mean that during an invasion attempt, the planet would be considered to have 600 defence for the purposes of working out % chance of invasion success. With the 10% bonus, would the invasion defense rise to 660? I'm dubious, as it says there is a 10% defense bonus which might not include invasion defence. If so, I will be removing my pylons and installing more obiviation barriers as they give me just over 3750 defense each before legion bonus; even with the 20% loss during invasion calculations, it still beats the 1200 from two pylons.

I believe I've heard that both the % boosts and your legion bonus count for invasion defense, but I'm not entirely sure. However, aren't Obviation Barriers better than Lazuli Pylons regardless? Or is it just because you don't want them being sabbed away?

Lazuli Pylon: 1 Space, 600 Invasion Defense
Obiviation Barrier: 2 Space, 1200 Defense = 960 Invasion Defence

Lazuli Pylon gives more invasion defense, per space, than a standard obiviation barrier.

Not sure where you got that number. From the debuff of 15% it becomes 1050 defense.

Still they pylons are better than the obv barriers - but not as good as a domain walker which (after debuffs) gives 510 def and 420 attack = 930 invasion defense (compared to the 600 from the pylon).

Whoops, thought it was a 20% loss. I've already maxed out on Domain Walkers.

But if you're really defending a planet would you not want obviation barriers with a decent amount of population so it'll take more time and energy to take it? Invasion defense has no effect on the damage they do to the population.

Though the ratio is higher with pylons, you are not taking into account how pylons will not do anything until they actually use the "Invade" button. Pylons will take nothing more than the RNG to overcome, while Obvs will require brute force and energy. I do not think the percent bonuses affect pure invasion defense, and for this reason, if you account for things like the concord station's bonus, the standard defense is a better option.

Another think I've been trying to consider, as well, is that you cannot Sab a pylon. Regardless, I'll remove two I've got and shove another Obiviation barrier on. My defense currently sits just under 60k on this planet and the population is 4770. I've squeezed the defence over 72k after two obv. barriers.

what artifact removes a planet from an enemies database?
I've had 3 planets stolen from me then removed from my database before I could regain them.

It's a planet flux.

The wiki describes it here: http://galaxylegion.com/wiki/index.php/Planet_Flux

Two things here.
1. This does not belong here, it belongs in the beginner's hub or in your own topic.
2. There are two different artifacts that can be used to remove the planet from the enemy's scans.
a. A "Temporal Flux Orb", also known as a "mini-flux" will remove the planet from the lists of all who have scanned it except for the owner. The reason that this is called a "mini-flux" is because it can be gained from a repeatable mission, and there is a restriction on it. That restriction is that the planet cannot have been attacked for one week prior to its use.
b. A "Planet Flux" is an artifact that removes the selected planet from the lists of all who have scanned it except the owner. This one has no restrictions on it. You can get this one either from a mission or as a rare drop from the Rare NPC "Dark Arms Carrier".

While population may deter some players from attacking a planet, players who npc a lot get bio vaps from dark arms carriers. And if someone in a strong legion finds a planet, legion coordination and/or bio vaps can make population almost useless.

Agreed. The only time population is of any effective use is when the planet owner is online and able to actively defend with cloning pods.