Best warframe in this game: The As- Wisp.

Build notes:

• Umbra mods, Adaptation and Primed Flow can be not maxed, as i do. Actually adaptation rank required is only 4 - more is useless.
• Adaptation and augur reach can be replaced with whatever you like.
• Hunter Adrenaline can be replaced with something like Transient Fortitude, if you wish so. I prefer adrenaline.
• Arcanes can be rank 0, it doesn't matter.
• Ultimate can be replaced by helminth. To what - the choice is yours.

How to play and where to play:

• Where: everywhere. This build is capable of doing almost every mission in this game. There's some where i'd prefer to pick someone else, but it very very situational. Mostly, wisp can do everything.
• How: simply. Place three of your flowers on current mission location (if mission is not static, then just go without them - it's not so important), and go on. Try to constantly stay in the air, because you are invisible while flying. Press Breach Surge when there a large crowds of enemies that should be killed.
  That's all!

For [Wisp], it's very easy to be useful and be powerful. Just relax and have fun!