This guide will let you know how to get Entrati Lanthorns in Warframe. You have to follow the simple steps in this guide to get it.
Entrati lanthorns can drop from any mission on the Zariman, but running missions that you can complete faster to farm them is recommended. So the only two would be mobile defense and exterminate on this tileset.
Once you are in your mission; for the most part, you have to break just about every crate you can find in the mission, as Entrati Lanthorns have a chance of dropping from destroyed crates (Not sure if they can drop from enemies. Though) however do be aware that they are fairly rare drops, so you may not get a whole lot of them in a single run unless you get lucky.