There doesn't seem to be much of an invasion guide around. From what I've gathered so far, you trade attacks with the planet until its population is lower than 10, and then you have a chance to invade? What's the cooldown on this ability? Does a successful invasion destroy all the buildings on the planet?

Thanks in advance!

invasion cooldown takes 24 hours, regardless of whether you succeed or fail
invasion costs 15 energy and (10n)³ credits, credits taken only on success
(n = current number of occupied planets)

before the recent patch i would have said all structures remain intact....
but with the recent patch there is a chance of a random event... one of the possible invasion events is losing a random structure

for some reason I thought it was 2(10n)^3

sorry, you're right... i left out the 2...

colonization cost = (10n)³
invasion cost = 2 × (10n)³

Which events trigger notifications for the enemy? Planet is attacked? Planet is successfully invaded?

an attk and invasion both as well as any artifacts used

now there may be a strategy forum about when you invade, i know our legion has an "invasion tip" on our group page (private)

Yeah, unfortunately I couldn't search the right keywords to find a good previously written guide.

One other thing worthy of mentioning that I just learned by trial: you can't use any previously built planetary buildings if you have not researched them!

Only tips I can think of is have as many people able to invade when you decide to try, in case you fail.

Use artifacts if you need to help you out reducing population or invasion defense.

Make sure you can invade (I have tried a few times forgetting my timer really annoying), funds etc, space for another plaent etc.

Try to get 2.7 total invasion defense or higher to get max chance of invasion.

i think it should be about 3/1 (your attk should be 3x's the def+invasion def to have about the max 90% chance success)

but of coarse there are other tactics to consider....

only need 2.7 to get 90% formula is % = att/ (3x invasion def) I will let you do the algebra to solve for att in terms of invasion def.

if that is correct, then what i thought is only .6 off of that calculation, and its not undershooting it its overshooting so its not exactly a bad thing (having a little more power to make sure you succeed)

if the invasion attack value being used is greater than you are expecting... it is normally because you forgot to count the modules on your ship that give a boost only during invasions