I was playing arena, and the opposing team had a flying cow, which ended up being their last troop left.
It activated migration and spawned another cow, fair enough. But then between these two, they spawned another 8. Every activation successfully spawned a cow, even though it is supposed to be 40%+ chance.
Also, each one was level 15, with 13 magic. I thought if a cow had 13 magic, it would spawn level 13 cows, which would have less magic and spawn lower level cows and so on.