Gro-a-Tog is a counterspell-dense blue-black control/tempo deck, so Abeyance is strong both for protecting your combo turn from Counterspell, Circular Logic, or Smother, and for occasionally shutting off a key turn of interaction. Hydroblast stays in the sideboard: it only affects red spells and permanents, and Gro-a-Tog plays no red cards, so it would do nothing here. Instead the plan brings in just the two Abeyance and cuts the 2 Mana Leak, since Mana Leak is redundant against a deck packing its own Counterspell and Circular Logic that can counter your counter. Swords to Plowshares remains excellent removal for Psychatog before it grows out of control. Prioritize protecting your Replenish turn and racing their card-advantage engine of Gush and Fact or Fiction before they can assemble enough mana to cast Psychatog as a lethal threat.