What Planets Are The Most Difficult?

[touchmyoldsnake 19]

So far, the only challenging system I have unlocked is Pluto, but the rest of them were easy easy. Does the difficulty change as you unlock planets and increase your level, or is it just a few planets that are the hard ones?

[JRMC 10,209]

Difficulty does increase as you progress.

[Lambchopzin 0]

Going by the level of the system in question is usually a good way to gauge it's difficulty, but yes, they do get more difficult as you go. There are also both easier and harder mission types. Try the Grineer Mobile Defense on Earth (Think it's called Lua). That's probably the first truly difficult mission you'll run into, depending on how you decided to progress about. I've only been able to beat it once out of probably 4 or 5 tries, and that's playing with friends (as opposed to a random PUG).

Also, all 3 factions get new abilities and units the higher up you get.

[DetergentPod 1,204]

I would have to assume it's Pluto. Before U7 even with Eris and Ceres I still find Pluto to be a challenge despite being able to breeze through Eris and Ceres without a problem.