I imagine every Captain Howler EDH deck looks a little different, with slightly different goals for how they want to leverage it, and that sounds like a fantastic commander
1 ready-to-play deck of 100 Magic cards (2 Traditional Foil Legendary cards, 98 nonfoil cards)
A lot of our job is bending the rules of Magic , or finding some tasty design space, and hoping that rules managers (who are incredibly awesome) deign it possible (thank you, Tabak and Jess!)
The activated ability is rather expensive though, so it plays best in decks that know they have to turn aside a single prominent threat
It is a Counters deck, looking to beef up our creatures with +1/+1 counters and weakening our opponents with -1/-1 counters, and running tons of cards that care about counters
Also, when you deny someone one of their fun spells, you can always copy it later on using a nasty Flawless Forgery