Generally, discarding a card to make a Food is costly in resource battles
A must for any collection but only while stocks last
All of Twitter is talking about today is which cards to clone with Mairsil the Pretender, what to do if you have multiple copies of Magus of the Mind and Shallow Grave in your deck, whether Kess is playable in Legacy
After all, even a First Edition Base Set card will dip in value dramatically if its dinged or scuffed
More seriously, I think Ravenous Rats perfectly embodies the value of a "discard one card of your opponent's choice" effect
If a noncreature artifact is returned to the battlefield this way and another effect would cause that artifact to be a creature while it is on the battlefield (such as the ability of March of the Machines), that artifact will enter the battlefield with an additional +1/+1 counter