I’ve created many many heroes, and tried to specialize at least once in every magical field, and I can honestly say that I liked every magic tree except for Chaos. One of my friends liked Chaos, because its basic spell and highest spells are good, but I personally didn’t think that whole tree was worth it. But YMMV.
My personal favorites are any magic trees that let you summon basic workers. That’s really awesome. You can get a huge head start if you can summon enough workers to fill in a mine or two at the beginning of the scenario/skirmish. But even magic trees that don’t have worker summons are good.
Even alchemy was a good tree because it lets you summon a lot of cool items for your hero. I remember one hero who built that all the way up, and then in every map, before we wiped out the AI, we’d meet in the middle and I’d make my friends some cool items.
The Undead are still one of my favorite races: I’d say come back to them once you’ve had more experience with the game. If you’re fighting a race that’s doing a lot of crushing damage, then Wraiths are the way to go.
I’d also be kind of leary of the dwarves. They’re the only racial type in WBC2 and 3 that I just couldn’t learn. I was always so frustrated with their lack of speed. They’re just so sloooooow. You can upgrade and make them faster by drinking a mug, but its one of the rare things in this game that you have to do manually. And I hate special abilities that you have to specifically use.
One of the greatest things about WBC2 and 3 for me, is that you don’t have to click on special abilities to use them. If you have a magical unit’s attitude set to Magical attacker or Magical Guardian, he will use special abilities and spells automatically.
So for example, White mages and Red Mages were mentioned earlier. White Mages can heal, and Red Mages can make your units immune to fire. Now in any other RTS (like Warcraft 3), you’re thinking “ugh, Micromanagement!”, but in Battlecry, just make them magical guardians, and they’ll automatically heal and cast fire immunity when they can, and if they can’t, they’ll still do their regular attacks.
And if for some reason, you’re a masochist and you LIKE micromanagement in your RTS games, then you can take them off Magical Guardians and Magic attackers, and they won’t do those things automatically, you’ll activate them by clicking or through a hotkey.