Sierra's last ability triggers whenever you sacrifice a Food for any reason, not just to activate a Food's activated ability
Zendikar Rising aside, I generally wouldnt recommend playing 19 lands in most Limited decks
Even Ravnica , with its plane-wide megacity governed by 10 philosophically-opposed guilds, is an obvious adoption of the famous Planescape campaign setting and matches many D&D urban fantasy tropes in the process
Expect the full-art versions to increase first, as the rainbow palettes often follow the path set forth by these cards.
On that note, black is the color containing the majority of the best reanimator cards and support, so all entries on this list will contain black in their color identity
Cards like these, that let you play as many copies as you want in a deck, are often worth a couple bucks even when printed at common or uncommon