I love Marichyasana B. C and D? That's another story.
These poses are rarely seen in classes unless you're an Ashtangi. I'd never seen them before my first primary series class.
Have a look at A here. It's a little bit more accessible than B.
The difference here is that you need one leg in lotus....or tucked under you if lotus is not okay for your knees. Some days are better than others for me.
This pose literally is wringing your body out like a dirty rag. I don't consider it complete unless sweat is dripping off my forehead! HA!