Mystical Dispute stays in the sideboard. Every spell they play is red or red/green, so it never gets its discount, and a three-mana 'counter unless they pay {3}' is a weak play against a deck full of rituals. Consign to Memory only counters a triggered ability or a colorless spell, so it answers nothing colored. Its real targets are Ruby Medallion, Ral's coin-flip trigger and the storm triggers on Grapeshot, and you can replicate it to hit more than one trigger. It costs one mana, so you can hold it up alongside other interaction on their key turn. Stern Scolding comes in as another one-mana answer to Ral, Monsoon Mage, which is a 1/3 creature spell with power 1. Spell Snare and Force of Negation both stay in. Many of their spells (Desperate Ritual, Pyretic Ritual, Manamorphose, Reckless Impulse, Wrenn's Resolve, Ral) have mana value 2 for Spell Snare, and Force of Negation can be cast for free on their turn against any noncreature spell. The slow cards come out instead: Quantum Riddler, Tamiyo, Kaito and Flow State. Your real plan is to disrupt them before they go off with Thoughtseize, Fatal Push on Ral, and efficient Counterspells, Spell Snares and Forces on their key spells.