Since black is the color of discard, it instead forces your opponent to have a smaller hand size. Two black creatures punish your opponent's hand in ways that mirror the Scrollkeeper and the Advisor. Both are rat shamans, representing a particular sect of the Nezumi: insect shamans.
These hand-size-surpressing shamans use incantations to summon and control insects to swarm their enemies. The incessant buzzing distracts and irritates, lowering a mage's potential for Cowed by Wisdom.
Note that the Mirage card Miser's Cage also punishes an opponent with a full hand. (Mise from Unhinged, however, is actually is a card-drawing spell. It refers to the Magic slang term referred to in its flavor text, not to the quality of being a stingy hoarder.)