Well, I wasn't attacking, I got rage from being attacked though (the ranged or no-retaliation stacks I let live attacked the dryad-produced thorns surrounding them - also casting Kamikaze damaging 7 of my thorn-stacks, each time one of my stacks suffered damage I gained 1 rage)
I have some patience but not an incredible amount, those were tedious battles but for the most part it was only pressing D (or clicking Defend) all the time until I had enough Mana to sacrifice/ressurect.
The funny thing is that I never got the Dead Scull to 0%
It was at about 12% when I finished the game... I could have gotten it to zero, but it would be useful only for very little battles left, and when I reached Murock I didn't feel like going back to the Labyrinth to finish it, I just wanted to finish the game...