Also, I found that the battles in the Bonelord expansion were made easier if you had rings associated with certain avatars. I think for the low-level encounters, a ring of the crocodile is the most useful. It puts out a 6/7 creature for only 6 mana!
I would strongly recommend you make use of the swarm. They're probably the single most important avatar that nobody uses. And with good reason, if you only consider swarm for their attack and special. But the real reason to use Swarm is that they're the fastest creature in the game. Thus, you can spend all of your mana summoning avatars before the battle, and then, on the first turn, cast the Mannaz spell and either summon more avatars or pump up your creatures with spells. My personal favorite is to cast precision on my powerful avatars, who can then always power attack without missing.
The changes to the Mannaz spell are good - it used to be a game-breaker spell. I would summon a Drake and a couple of Swarms, and then use the swarms to keep pumping up my mana and then summon more Drakes. This is no longer possible. And if you combine the new limits on Mannaz with the limits on mana during quest mode, usually the best Avatars you can summon during the fight will only be within the 6 to 16 casting cost range.
This game just gets better and better with each version!