The Assassin cube is a 4 hero mono-class cube featuring Mortimer's Lab as a gameplay macro.

Instead of drafting to a hero, drafting the Assassin cube requires you to draft to an archetype and build a specific deck. From there, one of the four Assassins may suit your archetype better than another, or maybe you just happened to pick up one card and one interaction that makes one hero stronger than another.

In general, you can draft:
Contract Fatigue
Double Trouble Combo
Dagger Aggro
Infectious Overload