Forma is an item that can be used to modify and manipulate polarities of warframes or weapons in the game, making for more efficient mod-setups. Modding in Warframe works like so – you have 8 “main” mod-slots, and each one have the potential of having a specific “polarity” – the polaritys on mod-slots indicate what type of mod (mods have polarities in upper-right corner) will fit “best” into a particular mod-slot. By using Forma you can manipulate the default polarity setup of weapons, warframes etc. by changing a mod-slot’s polarity into one that favors the mod-setup you want to play with :)
It’s quite easy to Forma a weapon or a warframe you simply go to your arsenal and select the weapon or warframe you would like to Forma (gotta have crafted a Forma for this first), then you go into the bottom-right corner and choose “actions” then “Polarization”:
This will bring up your mod-slots where you can click on the one you wish to alter polarity for, for each click you do- the polarity scrolls through the possible polarities to choose from:
Important note to make: is that after you Apply the polarity change you want, the weapon or warframe will reset to level 0 and leveling it up to 30 again WILL NOT give mastery rank! You only get this one time PER weapon/warframe/companion/archwing.
A very useful reason to Polarize a warframe for example could be to alter your Aura slot Polarity, so that you can have for example Minus (-) Polarity, instead of V polarity – so that Corrosive Projection and Energy Siphons can be used effectively instead of something less useful :)
Important Note to make: is that its a very Tedious process to Forma something, and you gotta make sure you are 100% confident in your choice of Polarity because it will affect all the future builds you will make for that weapon or warframe, and redoing it is just a waste of time as well as a Forma.
TIP: There is however the option of “Swapping polarities” in Action tab for weapon/warframe/etc. which could be seen in the picture of the Action tabs above – which could help out if you are to place a polarity in the wrong slot so you don’t have to re-do the entire Forma process :P
Hope this information helped :) GL in your future endeavours!