How to completely take over another empire?

[AnAngryYeti]

Is there a better way to do it than just making claims on every single system they have? At the current rate that I have influence coming in this would take an extremely long time despite the fact that I am massively more powerful than them. What would happen if I were to take over every colony they have (with claims)?

[cooltv27]

when an emprie has no planets left, all the systems they own become unowned

as for a faster way, you need to build a colossus (whiche requires an ascension perk) to gain access to total war, which doesnt require claims. or be an exterminator style empire

[_ALuX_]

Take every colonized planet. Thats what I do.

[lPaladinl]

Take all of their planets and they will no longer exist as a faction. However any territory you did not claim will still be unclaimed, so it's a free-for-all for anyone able to afford expanding into that are.

So while just rushing planets is the fastest way to finish a war and annihilate your enemy, you might want to take the time to control their territory first to prevent giving others the chance to take that territory before you do after the war ends.

[mirco]

Taking only the planets/habitats is a option as mentioned above.

And other more political way is to subjegate and integrate them instead. As you said, the only thing you are lacking is infuence. With subjegation you come out much cheaper for all of the worlds ( not to mention your new pops won't be so unhappy as when they are conquered ).
It is an much better trade with infuence for territory than conquering, the only downside is time.

You don't have to pay up all infuence as once either, nor can an other empire snatch any territory away from you without declaring war on you.

[Malecord]

There are only two alternatives to claim each system for aggressive expansion:
-Wage Total War and control systems directly: you can do that by building a Colossus.
-Vassalize/make tributary and control systems indirectly: you can do that by spending 1 point in the Domination tree.

Both have advantages and disadvantages. I usually prefer indirect control since it allows me to profit from the controlled territory without getting pop/territory penalties for tech and pop. During domination wars II only grab systems with strategic resources, ruined megastructures or border chokepoints (tributaries and protectorates are great resource generators but remain neutral during wars so you need to wall them off).