After Deathwing's demise, there will be need for new aspect of death, so that people wouldnt be immortal.
And then, Sylvanas shows, tells Tirion to place the chin on her and saying that she should be the death queen, so she ans her twins alex and Yzy could play with dolls, and for more brain function, to play chess with alex (white vs black, life vs death, u kno...)
Just random shit i tought of while i was watching the custom leaders pic.