Quick reminder of what the Covert ability does: " When this character attacks, choose one character without covert. That character cannot be declared as a defender."
With the latest expansion, Into The Forbidden City, Crab is now the only clan that features two different Covert characters - Kaiu Shuichi and Hiruma Skirmisher . As the so-called "dropbears" decks have already proven, Covert is a powerful tool that can create surprise province breaks. This inspired me to try making a similar deck with Crab.
For a splash, Crane, Scorpion, and Dragon can all give you an additional source of Covert. Of those, Crane appeals to me the most because of Admit Defeat . You can potentially Covert all but one of your opponent's defenders, then bow their lone defender. Political Rival also fits with Crab's defensive theme and helps cover your Political weakness.
The end result is something like this deck: https://fiveringsdb.com/strains/a4e9a214-d245-11e7-86fc-8e1ccf16fca4/view
I'm sure the deck could be refined further, of course. I'm interested to hear what people think of this more aggressive take on Crab that can still also pressure Dishonor and win on defense often enough to play the resource-advantage long game.