How do I make mods for Warframe?

You can mod any of your Warframes, weapons, companions, or Archwings inside the Arsenal. All you need to do is hover over the piece of equipment you are interested in modding and click the “Upgrade” button next to it. This will take you to the modding screen for that part of your loadout.

What is the rarest mod in Warframe?

Primed Chamber Mod is by far the most valuable and expensive item in Warframe. The bonuses it grants can be easily matched by well-rolled Riven Mods, but it’s considered a legendary collector’s item, to which it owes its’ astounding price.