Outpost Siege, Rose Room Treasurer, Rumor Gatherer, Sizzling Soloist, and Bosss Chauffeur all care, and other than Sizzling Soloist they are all pretty good cards
Grand Abolisher Chief: While it doesnt stop literally everything, this card is one of the best ways to make sure that you can take your big, exciting turn without interruption
The only other question is how to pay for these hefty activation costs and while mana abilities are deliberately exempted from both Zirda and Dynaheirs effects, that doesnt mean that we cant still abuse them to boost our total mana output
Snapcaster Mage, Liliana of the Veil, Gravecrawler, etc
ButI worry a little bit about the many situations where you cant really effectively tap your merfolk to get it going and those are definitely going to come up