You do not need to cast Awakening to regain the ability to cast Last Rites.
The Maiden will attempt to assist you in a fight, so choose your targets well.
You can send the Maiden down a lane alone, be careful though, as she represents a large portion of your combat power.
You can cast Smite on Mist Walkers and the Maiden of the Mist to damage or kill them.
Try to thin out Yorick's minions before you engage him, Mist Walkers will die from a basic attack or a single target spell.
You can attack Dark Procession to break the wall down.