Here are my ideas for new invasion tactics:

Neutron Star Matter Drivers

• Description: By bombarding the planet with ultra-dense material from neutron stars, we'll be able to increase the mass of the world and hence its gravity. The attack will be devastating and will turn this planet into a Heavy Gravity World.
• Cost: 400 BC
• Bonus to Advantage factor: depends on your level and enemy level of Heavy Gravity World Colonization
  
• Planet quality Drop: -10%~-30%
• Planetary improvements Destroyed: 30%~60%

Ice Cap Melters

• Description: By melting the polar ice caps of the planet, we will be able to bury our enemy in a watery grave. Rising seas across the globe will greatly decrease enemy defenses, but will also destroy almost all planetary improvements. This will also make the planet an Aquatic World.
  
• Cost: 300 BC
• Reduction of enemy Advantage factor: depends on your level and enemy level of Aquatic World Colonization
• Planet quality Drop: -5%~-10%
• Planetary improvements Destroyed: -90%~-100%

Nuclear Bombing

• Description: By attacking the planet with nuclear bombs, we can eliminate most opposition. However, this will make the planet a Radioactive World.
  
• Cost: 250 BC
• Reduction of enemy Advantage factor: depends on your level and enemy level of Radioactive World Colonization
• Planet quality Drop: -30%~-50%
• Planetary improvements Destroyed: -50%~-70%

Conventional Bombing

• Description: By attacking the planet with conventional bombs, we can eliminate most opposition. However, this will make the planet a Barren World.
  
• Cost: 350 BC
• Reduction of enemy Advantage factor: depends on your level and enemy level of Barren World Colonization
• Planet quality Drop: -5%~-10%
• Planetary improvements Destroyed: -40%~-60%

I see no need for a Toxic equivalent, that's what Spore ships are for.
 
It would be nice to have some other planet types as well, such as fiery and icy worlds that need colonization techs. I also want to make it so that based on alignment or species, a race could research a third technology for a given world type to bring the colonization ability to 125%.

It would be nice to have different types of asteroid bases. I saw some code for this in Dark Avatar that wasn't used.

Last, but not least, Terror Stars and Ascension Bases. I notice that no improvements can be made to an Ascension base. I assume this is a glitch of some sort; they should be able to have weapons and defenses like other starbases. Same deal for Terror Stars. I also want to make Terror Stars move faster with some additional upgrades. I am thinking 1 pc/wk by default, with upgrades to 2, 3, 5, and 7 pc/wk, with each being rather expensive (maybe 500, 500, 1000, 1000). As is, there is no point in using them because they are so slow and defenseless.