How do i upgrade to 6 npc slots ?

The Glaviz/Zolazin mission chain gives two along the way, and the Lazuli chain (starts with "A Syndicate Trap") gives two.

and the new shadin mission gives 2 more for a total of 8.

whats the new shadin mission what level do you need to get it

250 i believe, but im not sure as i dont have it yet. 4-9 more days till i get it depending on which NPCs i get on my tab.

http://galaxylegion.com/wiki/index.php/ ... _Abduction

Somewhere between 230 and 300 I think. Could be wrong though, but apparently no higher than 305.

there is a mission chain that adds just one NPC slot.

I haven't heard of that, what is it?

No there is not. If you complete a cycle of various missions that unlock a battle, it will temporarily add an extra spot in your NPC area if all of your spots are already filled. After you kill something, anything, on your NPC tab, you will go back to your established, permanent maximum. You do NOT keep the extra spot permanently, and you do NOT get a fresh NPC until you clear a spot for one. For example, if you have 2 permanent slots and you complete a cycle of the mission (Crimson Confrontation, I believe) that unlocks a battle with the Crimson Shrieker, you will TEMPORARILY have a 3rd NPC. If you kill the Shrieker, you go back to 2 spots. If you kill one of the other NPCs on your tab, the Shrieker will move into its slot, also returning you to 2 spots.