Talk:Void Keys/@comment-82.216.251.157-20140310120329/@comment-24067351-20140319122807

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

If you want the best one, go on either casta in ceres or yemaja in sedna.

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.