traveling this week, so will be playing, but intermittently. Actually I think yesterday was the first time I have not played my 5 GW battles, and this morning was the first time I saw what happens when you play catch up. I actually did not know if you had to play the makeup games in the previous CotD or that days until this morning.
Of the 8 battles I just played, 6 had at least 1 devour troop. Of those 6, I played full impervious teams (so not CotD, I generally go Carnax, Dracos, Plague, Behemoth) against 4 of them. I won all 4 of those. Of the 2 that I thought I could get away without full impervious, there were 3 devour attempts, and all 3 were successful. So I now revise previous statements and believe that 40% actually means 80% for your opponent, and 0% for you.
@Diane For Kraken, you really just need one troop with impervious in the last spot. If you have Behemoth, I highly recommend grinding him up. The combination of impervious and gain life on 4 or 5 match means that is just could care less what Krakens do. Not to mention he does decent enough aoe damage and a little bit of a fill.
For Aspect of Famine, you generally want something in the first spot that can regenerate either life or armor regularly. AoF gets spread between life, armor, magic and attack. So as long as something is regenerating or you have some other way to regenerate, you can withstand it. Death bothers me more than Famine as his life drain of 2 per turn can go quickly. But even for him, I tend to focus on just killing him first. So this morning against Pison, Famine, Death, Famine, I went off CotD and brought in Amira, focused on filling her first and was able to one-shot Death out on my third turn.