Only neutral planets can be colonized. Planets controlled by a rival empire must first be bombarded in order to turn them neutral and allow you to colonize them.
Ships with the ability:
- Protev Colony Frigate
- Missionary Vessel
- Jarun Migrator
- In addition to each factions' specialized colonizing vessels, each race has a Capital Ship has the ability with a unique buff. This can be especially useful if you don't wish to tug along a vulnerable colonizing vessel.
- Akkan Battlecruiser (Colonize)
- Progenitor Mothership (Colonize)
- Jarrasul Evacuator (Colonize)
You can colonize any neutral planet, even if there are enemies in the gravity well. The only requirement to using this ability is that the planet is neutral. This means you can colonize a planet while you are still fighting the militia or the enemy for control. Once you control a planet, you can start building defensive structures there to consolidate your control of the gravity well. Fortunately, construction vessels are easy to kill, so if your opponent does this to you, just quickly kill the constructors before he can actually build anything.
When fighting militia, you should attack and destroy the Krosov Siege Frigates first. Once these are removed, the militia are incapable of bombarding the planet. Even if you do not defeat the militia, you will remain in control of the planet. There are several tactics you can use in combination with this. One of the easiest is to build defensive structures to defeat the rest of the militia, or to repair your own ships to keep them alive. Another option is to simply leave the militia intact and move on. The militia will actually defend your planet from attackers, although you will be unable to build anything there while the militia are still around.
If there are no more than one siege frigate, it's actually possible to send colony frigate to colonize the planet, build a defense turret, and kill the siege frigate before it can successfully bombard the planet. This strategy takes a bit of practice, since if you get it wrong you lose the planet. Make sure you have enough antimatter to use colonize before you jump in (you'll need 190, since you'll lose 100 when you jump)
One way to annoy the enemy is to colonize a planet he's just bombarded, forcing him to bombard it again. Especially when he's using capital ships with low bombard damage, such as carrier-class capital ships, this can take a while!