Familiars is a combo-control deck that generates infinite mana and cards via Sunscape Familiar, Snap, Archaeomancer, and Ghostly Flicker loops, winning through Murmuring Mystic tokens or God-Pharaoh's Faithful life drain. Pyroblast is your best disruption here, hitting their key blue spells like Snap, Ghostly Flicker, Meeting of Minds, and Mulldrifter at instant speed while also acting as a hard counter. Dispel is largely redundant with Counterspell and Pyroblast available, and Ethereal Haze and Thraben Charm do little against their game plan. Keep Skred active to handle Murmuring Mystic and Sea Gate Oracle, and prioritize using Ephemerate on Mulldrifter to maintain card advantage while holding up Counterspell and Pyroblast to disrupt their loop attempts.