Interesting concept...
By 'Activated' creature ability, this doesn't include the automatic triggers from creatures, correct? (Bioluminescence, Vampire, and Venom, for example). What about flying weapons? Can it learn new/multiple abilities each time a different creature skill is activated?
What is the ability called, exactly (just doppelganger)? Finally, does its ability also apply to your creature on the field as well? (Meaning, if you played this card and then burrowed a Shrieker before ending your turn, would it just take the burrowed ability)
{Sorry for the questions}
The only cards that this wold be pretty useless on would be creatures such as an Elite Otyugh (who you couldn't eat anyway with the 1|6 stats), or an Arctic Octopus (the Doppelganger would be frozen still). However, it splashes well with other elements almost perfectly (speed rainbow galore!), and it's also designed to the point where the opponent (who's facing one) has to decide the correct order of using his skills, or else...).
I imagine this would also be devastating with Nymph cards, if you had them.
(P.S. - the upgraded card's background looks a little off for some reason. Why is the
mark cost faded? ^^;; )