Talk:Void Keys/@comment-203.4.183.34-20140309232427/@comment-24067351-20140319123042

If you want the easiest mission. Go Cambria survival on earth or  Lares defence mercury

If you want the best one, go on either xini in eris defence (leave at wave 10) or yemaja in sedna survival.

or look at

http://warframe.wikia.com/wiki/Survival

or

http://warframe.wikia.com/wiki/Endless_Defense

to see in you own opinion which places are the best to farm.