You've got several ways of making those merfolk unblockable (such as Rogue's Passage), and plenty of ways to break a stale board state in Curse of the Swine and Wave Goodbye
These sleeves combine premium durability with excellent clarity for serious gamers and collectors
Conroe Sports Cards & Collectibles Show, Hyatt Regency Conroe, 1001 Grand Central Parkway, Conroe, TX 77304
This, and the following Morden Horizons sets, we now know produced powerhouse cards that affected Modern, and even Legacy
If you can bounce one of their spells during their turn in which they cant recast it that turn, you could then play Comply during your turn to make sure they cant cast it during their next turn
Many of my archetypes work on that premise, like my Succubi with Block Attack