Thanks for the responses, guys.
I got my first game with the new expansion in this weekend, with my friend and I playing the default spellbooks.
I ended up trying a mini-version of my fortress strategy with the default book, and it sort of worked, but the game was ridiculously long.
I brought out an Acolyte on turn 1, then a Libro Mortuos. On turn 2 I cast the the Altar in the Acolyte's zone so that she could immediately start putting tokens on it, and brought out a Death Ring to speed up my casting.
I underestimated just how quickly the druid's vines could spread across the map, especially with the Vine Tree being used to put them out faster. Fortunately for me, my opponent inadvertently helped me protect the Altar by putting out a Bloodspine Wall in the back right corner of my side of the map. He used it to yank zombies through with his Thornlasher, and had a Vince Snapper waiting for the victims, too. He did manage to take out a zombie or two that way, but the wall also kept his creatures from moving into my area, too. I put up two Wall of Bones to cover the the spaces in the back left and back center, and used them to hold of an opposing Kralathor and Raptor Vine for several turns, chucking Reassembles at them when necessary.
I knew that Kralathor was going to come bursting in like the Kool-Aid man before long, so on my side of the walls, I brought out Shoggoth-Zora and fed him a crawler or two in preparation. I had Shoggoth-Zora guard before Kralathor came through, so that the hit came on someone that could take it and hit back. I then put the 3rd wall of bones up where the destroyed one had been to buy a couple turns before the raptor vine could follow him through, and hit the isolated Kralathor with everything I had.
The delaying action worked, and I got the Altar activated, which was the beginning of the end for the druid. He made a final rush at me using Togorah and every other medium-large creature he could get out, but the accumulated damage from the Altar and my creatures worked to systematically destroy any threats, and a Zombie Frenzy gave me the last push I needed to end the game.
Observations:
The Altar was amazing once it was activated, but my inability to kill any opposing creatures early on meant that it took a looong time to get going. I still think that a build around the Altar could be doable, but I need to speed it up significantly if I want to be able to finish games in a remotely reasonable amount of time.
Death Ring is great. In addition to the obvious stuff like the actual creatures, it also applies to Reassembles and the spell from the Deathshroud Staff, since they're necro spells. And with one or more spawnpoints, you make back the invest on it really quickly.
If I have a full 6 Wall of Bones in the spellbook, it might be more action-efficient to let the other guy knock them down and then replace them, instead of trying to keep them up using Reassemble. On average, Reassemble will remove 6 damage, but a completely new wall will have 12 health for only 2 more mana.
Without the Archer's Watchtowers, I never tried bringing out any Skeleton Archers, since they don't work well with walls without the towers. I'll definitely have to try that next time.
All game, I was really wishing I had more mana. That was probably due to me being excited to play with my new toys and playing spells just because I could, but I'll definitely have to keep that in mind for future games.