Mulligans
General Mulligans
The best Mulligan choice is the Dalaran Librarian. But use it wisely, you only got 2, and need to be silence 6 of your minions.
Unless that's why you need Unsleeping soul.
Aggro Mulligans
This combo is always a good choice for a clearly combo.
It’s easy, like the Lich King said:
“Silence Priest, the light will be deaf to your cries for mercy!“