I'm not sure but I don't think you can get infest ability from a mutation...at leas, I've done several matches with a timebow oty+graveyard+druid, and got few creature with each ability, but none with infest; I think there's statistical evidence that you can't get it from a mutation...
The weirdest thing I got was not from a mutation, but with the new eternity+skeleton mutation-for-poor ability...I rewound a skeleton, it became a skeleton (so it's an old skeleton), turn after it was rewound into a mummy, which in the end became a pharaoh...The first skeleton was a keleton from a skeleton from a mummy of a pharaoh...oldest skeleton I've ever seen...