Bonus Round is especially good in Two-Headed Giant, where your teammate can copy his or her spells, too - the reason this card was designed in the first place. But because your opponents can benefit from the effect, too, Bonus Round is a pretty fair card.
Are There Cards Similar to Bonus Round?
This card is better than Howl of the Horde, a similar card from Khans of Tarkir that only copied your next instant or sorcery spell. It also cost three mana, and had a Raid ability that allowed you to copy that next spell an additional time if you attacked with a creature that turn. While that’s not a bad card, Bonus Round is certainly superior.
The two-mana Reverberate (RR) copies just one instant or sorcery spell, but it’s at instant speed and allows you to copy a spell cast by any player. Some players feel that despite the potential power level of Bonus Round, Reverberate is actually the better card. Is that true?
Legacy Storm may not need a card like Bonus Round, but it is a card that certainly is interesting. Doubling your spells in that kind of deck is excellent, but can it actually fit into the deck? I’m not sure you’d find room for this three-mana card in Ad Nauseum Tendrils, for example. It would be better in U/R Gifts Storm in Modern, but alas, Bonus Round isn’t legal in Modern. It’s possible some players will try it, though.
How Good is Bonus Round in EDH (Commander)?
One of the more popular homes for Bonus Round will easily be Mizzix of the Izmagnus and Melek, Izzet Paragon spellslinger EDH decks. Adeliz, the Cinder Wind and Kess, Dissident Mage are two other Commanders that can use this card, due to casting lots of instants and sorceries in a turn, too. Bonus Round is right at home in these decks, since there will be plenty of occasions when casting it will be most advantageous for the caster.
What’s the Best Way to Use Bonus Round?
While Commander will likely be the format that will break Bonus Round the most, Bonus Round is particularly awesome in Two-Headed Giant, the very format that it was designed for. In Two-Headed Giant, you have two teams of two players that share a life total and work together to defeat the other team. Bonus Round is great for helping your teammate to cast instant spells with greater effect. While Bonus Round may be more powerful in Commander overall, it’s probably the most fun to cast in Two-Headed Giant, where a well-timed cast can win you and your teammate the game.
Kudos to the Battlebond design team for creating a really good card that’s both fair and extremely powerful in the right context. While there’s little doubt that EDH will be the most popular home for this card, Bonus Round is definitely a great card for the format it was created to be played in.