When it comes to the melee weapon scene in Warframe, it is starting to become very hard to make anything new or interesting. The incarnon system for melee weapons make them more usable, but they are still pretty lacking. This goes for the Ekhein, a new hammer added in Whispers in the Walls. It does have a great niche that fits into the new Tennokai system. However, outside of that, it is a little boring. But here is an easy build to use for it if you like it!
An Easy Ekhein Build in Warframe
Here is the build I have been using so far:
I use a mix of radiation and Corrosive for maximum effectiveness against armored enemies. Adding heat gives a damage over time that is sorely needed. Considering the Tennokai helps with more damage output, you can probably remove the heat mod and mix in Killing Blow you can if you want to forma it. For choice of melee arcanes I would most likely try and use Melee Exposure considering you can stack nearly three times the corrosive damage output.
But this is an easy build to go for general use if you like using it. I hope this build helps you in Warframe.