Warframe: The New War Quests - Kahl 175
Having done the Chimera Prologue, you move on to the Erra and Maker mini-quests. This cues in The New War. The first quest completed in this story arc is Kahl 175, in which you play as a Grineer. This actually gives depth and empathy to a faction which up to now has primarily been an enemy, and cannon fodder. The sense of desperation, bravery, and self-sacrifice is palpable.
This was excerpted from a nearly two hour live-stream. So if you have already watched that endeavor, titled "Warframe: War is the unfolding of miscalculation," then you've seen this. If you haven't, and you want to, the link is here:
https://youtube.com/live/uJjFufGX5aM