here is my Kuva Fortress easy build, doesn't interfere with game play as you do not have to chase kills way outside a max range [Limbo] rift. You only have to cast your 4 (Cataclysm) once and your 2 (Stasis) once, you will need to cast your 2 twice when the levels get into the 70 range. You only cast your 2 again so when you leave the extractor for the next one, it doesn't get one shot as Stasis releases, but as I mentioned you only really need to do this as enemy levels increase to around 70 to be safe.