Cool Card Design of the Day
10/25/2016 - I won't have time this weekend or Monday to run an art challenge. If you're inspired to make a card with feed, or related to feed or Baby Kraken in some way, feel free to share it in the comments.
Feed varies from monstrosity in two big ways. First, any player can enlarge your creature and whoever does will be rewarded. Second, it can be activated in response to itself; which means that when the first person feeds it, everyone can respond by feeding it further. Once that flurry of feeding is done, your creature will be up some number of +1/+1 counters, and everyone who contributed will receive some rewards, but then it can never be fed again.
While feed could work in a duel, it would be most fun in a multiplayer format. My biggest concern is that it's counter-intuitive: It's far from obvious that you're expected to feed it multiple times (it's been a while since they've made a Goblin Cannon), and a good chunk of players will be turned off by the idea of feeding their opponent's creature or of rewarding their opponents for feeding their own (though I expect that's mitigated by putting it in a multiplayer product).