So after a bunch of games in advanced mode, I think I've nailed a strategy for consistent wins. I do owe some thanks to the contributors of this board - it's been a great resource.
Note: this is only the base advanced game - no expansions.
In the advanced game, the real strategy happens while drafting the defender deck. Since your success in the game is dependent on drawing, I found that building a small deck is a great way to ensure you get what you want, so go for thin columns where possible, but make sure you get a good chunk of burners.
For essential cards, the owls and level 4 fountains. With a small deck, you'll almost always pull an owl, possibly two in one turn, giving you a level 4 fountain and a few burners to plant it with. You'll also want hedgehogs to protect against ravage cards, and a few elephants to get rid of dangerous cards.
This way, within a few turns, you can build a wall of level 4 fountains. Since the only thing that can remove a level 4 fountain is a ravaged 0 or 3 elemental, use hedgehogs to remove the ravage flame cards if they appear, and use elephants to wipe out any 4 elementals that appear.
Using this method, even if a 4 slips through and kills a fountain, with the small deck and owls I can almost always grab and plant that 4 fountain again within the next two turns.
You'll also find yourself burning through the deck quickly, so don't USE the owls unless you need to. I'll run out of cards to draw late in the game - with about 2-3 turns left, but at that point it won't matter, I'll have what I need in my hand.
All in all, I'm having a lot of fun. Almost feel like the recruitment phase is a game in itself. Can't wait to get Castellion and give that a whirl.