I missed it earlier, but Baloth Null facilitates rooftop storm combo significantly...

Rooftop Storm + Sidisi, Undead Vizier self exploit fetch Sidisi, Undead Vizier self exploit fetch Baloth Null (Return 2x Sidisi to hand) fetch a zombie sac outlet (e.g. Nantuko Husk) and a second recursion zombie (like Baloth Null #2) and you have a tutor loop. Gray Merchant of Asphodel is an easy way to close out the combo.