I'm not sure if this ever came up and whether this is in the right page so feel free to move this to the correct page,but while i was using the Gravitic Amplifier on my planet,i keep wondering what is the maximum passive defence,attack and cloak for each artifact that increase passive abilities.When i search the wiki for it i have to keep going from one page to another.Feel free to add all the artifact that add passive abilities that doesn't cause the planet to become invincible.So here goes.

Gravitic Amplifier (Cap at 2100 passive defence per planet) Dropped from Lazuli Fabrication Plant
Increase passive defence on Planet that are Very Large or greater in size by 100

Conductive Pillar (Cap at 3000 passive attack per planet) Dropped from Crimson Scythe
Increases planet passive attack by 110,If used on a Metallic or Dyson planet, this bonus doubles.

Interspacial Fold Generator (Cap at 3100 Passive cloak per planet) Dropped from Lazuli Fabrication Plant
Permanently increases the passive cloak of a planet by 100.

Xecti Ensconcing Field (Maximum of 15) Dropped from the NPC Xecti Agent
Increases the planet's passive cloaking and defense by 80

Hyper-Dimensional Anchor (Maximum of 15) From the mission Dubious Intent
Permanently boosts a planet's passive cloaking by 90 when used. Due to risk of Octafari control, it cannot be used on Oceanic worlds.

Siladon Shield Upgrade (Once over 7000 passive defence,cannot be used) From Legion Mission The Siladon Event Task 1: Upgrade Siladon Shielding
Amplifies a planet's existing shields and defense, permanently boosting its defense by 300. Usable on planets that already have between 1000-7000 passive defense. (250 energy for one use).

Eruption Channeler (Cap at 1000 Note:Use it one more time to get it to 1050) Dropped from Lazuli Factory Complex (ranks 50-180) and Lazuli Refinery Center (ranks 100-600) (As stated below,it only works on Volcanic planet)
Adds a permanent 50 attack bonus to a volcanic planet

Thermionic Intensifier
Transforms a volcanic planet into a Demon world,
enhancing its size by 1, attack by 800, and all resources by 1.

Gift of the Void: (Cap at 500 passive cloak): Dropped by Christmas holiday NPCs.
Permanently increases the passive cloak of a planet by 40, up to a maximum of 500.

Magnetosphere Charger (Cap at 3500): Bought in Battle Market
Permanently increases a passive ability on the planet (of your choice) by 10% + 50, up to a max of 3500.
Choices are: cloak, attack, or defense.

Clandestine Revisions (Unknown Cap): Bought in Mission Market
Amplifies a planet's existing cloak, permanently boosting its cloak by 250.
Usable on planets that already have between 1000 - 5000 passive cloak.

Gas Igniter Rod (Cap at 1000 attack) (As stated below,It only works on gas planet)
Adds a permanent 50 attack bonus to a gas planet

Crimson Intelligence (Successful completion of the Legion Mission Assault on Crimson Deep-6 Task #2, Assault Base Interior)
Permanently increases a planet's attack by 25%. Can only be used once per planet.