Disruptor Flute naming Doomsday taxes their combo turn by three mana, which can be enough to blow them out when they're tight on resources after Dark Ritual. Mindbreak Trap can exile their countermagic like Force of Will and Daze for free once they've cast three or more spells in a turn, which often happens on their combo turn, protecting our own disruption or clearing the way for our plan. Trinisphere remains excellent here since it taxes Dark Ritual, Ponder, and their cheap cantrips, making it very difficult for them to assemble the Doomsday pile and protect it with Force of Will/Daze on the same turn.