I'd start out with laying out od along the top of the screen, and then resist any incursions that the AI was trying to make into my space. It'd waste enough of its mana on futile attempts at breaking through at spaces other than its main concentration point that I'd be able to hold out the entire game.
I'll see if I can find some time to play some multiplayer. I'm sure I'd fare worse against you (especially now that I've given away my winning strategy!).