Grixis Affinity threatens to bury you under large artifact creatures and card advantage engines like Thoughtcast and Ichor Wellspring, but their most dangerous card against Dimir Faeries is Krark-Clan Shaman — it can tap repeatedly to deal 1 damage to each non-artifact creature, annihilating your entire board of 1-toughness faeries, so prioritize answering it immediately with Counterspell, Cast Down, or Snuff Out. Hydroblast comes in to counter Thoughtcast and can destroy Seat of the Synod to reduce their affinity count at a critical moment. Relic of Progenitus disrupts Blood Fountain and Refurbished Familiar's graveyard recursion, which are key value engines that let them rebuild after you stabilize. Murmuring Mystic is a resilient threat whose 5 toughness blanks Galvanic Blast, and it generates a stream of Bird tokens as you deploy your instants, snowballing in longer games. Ninja of the Deep Hours and Thorn of the Black Rose come out because both are fragile to Galvanic Blast and too slow to matter in a race where tempo is everything.