This is the weapon (with a 25% roll on electricity so it already has base electricity damage of 13.5) that I used to solo Lephantis in ODA (Orokin Derelict Assassination). I know there are weapons better suited to take on Lephantis, but it was the only weapon on me that could do the job. Lephantis is weak to corrosive, blast and slash damage and with a Rhino built for armor, duration, efficiency and strength (armor and strength for Iron Skin and duration to slow Lephantis down with his Rhino Stomp) it is easy to take Lephantis down. The 60%/60% element and status chance mods could definitely be replaced with their 90% element counterparts for more damage, but just take out the [Serration] to fit them all in.

Edit: I updated the build with the addition of a forma and replaced [Serration] with [Vital Sense].

This can build can be replicated with no forma just be sure to put [Heavy Caliber] ([Serration] if you don't have it) and [Split Chamber] into the default V polarities. Again, you can get more damage out of the build if you don't have the second damage mod and replace one of the 60/60 mods with their 90% element counterparts.

The resulting build will look like:

Point Strike, Heavy Caliber/[Serration] (rank 6), [Split Chamber], [Infected Clip], [Stormbringer], [Thermite Rounds] and [Rime Rounds].