The basic idea is mothdust changeling/mutavault triggers descendant's path for any creature type so if you set up the top of your deck to cast emrakul, then you win the game. Simple.
Alternate wncon is the good ol standbye, show and tell.

The list

lands//22
2 ancient tomb
2 city of traitors
3 mutavault
4 tropical island
4 misty rainforest
1 wooded foothill
2 flooded strand
3 island
1 forest



creatures//11
4 emrakul, the aeon's torn
3 progenitus
4 mothdust changeling

spells//27
4 descendant's path
3 worldly tutor
4 show and tell
2 personal tutor
4 force of will
4 spell pierce
4 brainstorm
2 sensei's divining top



The deck is just as fast as normal show and tell decks, but also has the luxury of actually casting emrakul for free, instead of just putting him into play, or paying full cost. Descendant's path is no quicker than sneak attack, but at least you keep the emrakul if he doesn't manage to kill in one swing. The hands can get a little clogged sometimes with emrakuls/progs, but that happens with every show and tell deck. The deck could still definitely need work.