Hydroblast only hits red spells and permanents, and this mono-blue/black Gro-a-tog deck plays no red cards, so it stays in the sideboard. The extra Annul also stays out: the opponent's mainboard has no artifact or enchantment spells for it to counter. Make no swaps and lean on Counterspell, Mana Leak, and Swords to Plowshares to answer Psychatog before it gets large off their own graveyard. Standstill is risky since they have strong card draw already (Gush, Fact or Fiction, Impulse), so lean on proactive removal and counters instead. Wrath of God remains an excellent clean answer to a lone Psychatog.