A lot of the early characters that you bring into play have a low strength, so Only So Much Room is going to be useful at mitigating that, forcing one of those cards back into your opponents hand, while allowing you to get a character card back from your own discard pile
The most common, and perhaps the best way, to use this Song is against your opponent by returning one of their cards back to their hand
This orc shaman offers a powerful ability for decks like Prosper, Tome-Bound and Etali, Primal Conqueror focused on casting spells from exile but often does nothing the turn you play it and lacks a meaningful body if you cant cast spells from exile
Tutoring for an Equipment when it enters is ripe for abuse with blink and flicker effects, and then doubling the effects of Equipment could easily bring the game to a close before it even started
Lucky Dime Decks Lucky Dime from Into The Inklands has been a huge threat ever since it was first printed, and now it can easily set up combos that can win you the game in a single, explosive turn