-the setup is almost the same: 1 group - 1 Angel - Marks - 1 group, 1 group. While the Angels are distracting, we separate them and don't use them to attack the Griffons directly, but simply move them downwards. The Griffons attack the Angels. The Marks move down to the Griffons' positions. Then, the Angels go into defense. While the Angels are taking damage, we eliminate the stacks that move first, but only reducing them by half. Then, the Angels lazily attack with their half-health stacks (from a defensive position). The Marks eliminate the remaining full-health stacks, and with a slightly stronger Valkyrie, the Angels are left with 20-30 hit points if everything goes well. Something like that ;) In a real game, the Valkyrie is usually stronger, and there's something useful like defense or offense, so it's quite possible to win in this way without any losses.
P.S. I said that all the Marks must survive. What are you talking about with single Marks?
I don't believe it. I did something similar, even better - single Marks make it easier to win (higher speed + the group stack always attacked the Griffons, difficulty 160%). There's simply not enough power, just a little, but not enough. Either you messed up something with the parameters or the number of troops. In the initial composition I suggested, there are enough troops, but in your reduced version, there aren't.
