He has mastered a 'formidable' amount of material.
The mountains were a 'formidable' barrier.
a 'formidable' enemy/opponent/weapon
(..) - The Republicans will get in line. - Not the Republicans, the Democrats. I spoke to Jackie Sharp. When she heard you developed this plan... She's a formidable woman, Claire, and very persuasive. - Remy Danton. - Remy, we need to talk about Jackie. Such a nice night. Let's go somewhere outside. (..)2016 TvShow: House of Cards Title: Chapter 45 Season: 4 Episode 6