Hey guys seen a lot of question about eidolon hunting so ill try and be as detailed as possible as to what you need for the fight.
WARNING SPOILERS do not read further unless you have completed The War Within quest!!!
1st you need to have gotten your mote amp from quill onko on cetus. lvl it to 30!
2nd the frames used are
there are a lo of different builds for volt but i think this is a good all around eidalon build.
thats a pretty standard build for eidolon fights there are some crazy builds you can do that have even higher power str but require the umbral mods.
As with everthing in wf these are not the only builds that you can use just tried and tested 1s that work. Once you understand the fight better feel free to tweak and change things as you see fit.
So now for eidolon damage setup the most favored weapon for the teralyst is the Lanka. You can build it from the dojo’s energy lab. http://warframe-builder.com/Primary_Weapons/Builder/Lanka/t_30_22032203_132-0-5-137-1-10-138-7-5-140-2-5-141-3-5-150-4-10-159-5-5-847-6-5_132-8-137-7-140-9-141-6-150-8-159-5-847-9-138-6/en/2-0-20/166788/0
Now as with everything in wf you can use other weapons, your looking for high damage RADIATION and or puncture weapons. A lot of different weapons can be used if you have a good riven mod for it.
Finally is eidolon armor theres a lot of math here so I the math midget will leave this link to explain it. https://www.youtube.com/watch?v=y4lXM27EzLU
Now as far as the amp you should use. theres a lot of ways to do it but this vid should cover all the baisics
I hope this helps guys join us in discord if you have more questions!!