This is a mirror-adjacent matchup, so Surgical Extraction is excellent for stripping a resolved Murktide Regent's fuel or answering a key card before it can be replayed. Dauthi Voidwalker is an efficient evasive clock that also exiles opposing cards heading to the graveyard, hampering their Nethergoyf and Murktide Regent. Flow State is cut down since card selection is less important than proactive disruption and threats in this grindy mirror. Drown in the Loch is weak early against a deck with an empty graveyard, so we trim one copy for more targeted interaction.

A second Toxic Deluge (paid at X=2) is a premium sweeper against a token-heavy strategy built around Ocelot Pride and Ajani, Nacatl Pariah tokens, wiping their board cheaply. Dauthi Voidwalker races well since it dodges Swords to Plowshares' main downside window less often and pressures life total in a life-gain matchup. Drown in the Loch is weak early when their graveyard is empty, and Kaito is vulnerable to their wide combat math and Wasteland-heavy manabase, so both come out. Keep an eye on Karakas bouncing Tamiyo in creature form.

Damping Sphere cripples Ancient Tomb and Eldrazi Temple by capping them at one mana each, badly slowing their explosive starts, and it taxes their spells if they chain them. Surgical Extraction can strip a Thought-Knot Seer or Reality Smasher off the top of their draws once one hits the graveyard. Kaito comes out since it doesn't pressure their big colorless bodies well; the two extra fetches are cut since Wasteland effects matter less and we want fewer cracks into Eldrazi Temple mana. Watch out for Chalice of the Void on 1, which can lock out Fatal Push, Thoughtseize, and Brainstorm.