Yes, but I've never seen such tactics used online. Online, if more than two wall segments are needed, they don't use a single stack; instead, they send units in groups of one, which is what your initial battle scenario shows. Staying behind a single wall to unleash a powerful spell on the second turn and reduce the problem to two walls – yes. Staying behind a wall to cast something unpleasant, like Slow or Curse – yes. But I haven't seen a case where a wall is placed right next to the enemy, and then two other walls are placed somewhere else. Yes, I don't watch everything, but the most interesting battles are usually highlighted. If you can provide a real example from online games, that would be a different story. But I don't understand the reference to online play.
I assume Obi and Marlo were on the same wave with Dirty, and Obi's solution involves an instinctive first move, which is more important for some. But the strategy of looking for the "brightest" spot isn't always a good approach.
And can you provide a link to the author's solution, which is hard to find?
I apologize, is it just me, or does page 243 not open? For some reason, any attempt to open it opens page 242.