Teferi, Time Raveler is the same way, as his passive power prevents players from casting instant-speed spells the moment he touches the table, preventing counterplay at a very early turn: as early as turn two if you can get some quick one-cost mana ramp out turn one
This can be absolutely back-breaking for certain decks
This one, however, I think is sadly going to be too inefficient for most people
Deep Sea Diva - [3-5] On Normal Summon, works with any Level 3 or lower Sea Serpent-Type Monster in the Deck
The only saving grace here is the Pain lands present (Underground RiverUnderground River, Adarkar WastesAdarkar Wastes, Caves of KoilosCaves of Koilos), as well as a very welcome reprint for Hall of Heliods GenerosityHall of Heliods Generosity