Body Double if you mill opponents and Vizier of Many Faces if you mill yourself
It seems like this went over well with the cinemas and Disney
Blue decks generally tend to have a lot of cards in hand, and dont need the help all that much, so youd likely be using this to help an opponent as much as yourself
There's still lifegain stuff like Voice of the Blessed, five color things like The Kami War // O-Kagachi Made Manifest and all the domain cards from Dominaria United , heroic or aura type things with cards like Stormchaser Drake and Light-Paws, Emperor's Voice, good build around planeswalkers like Chandra, Dressed to Kill, fun graveyard stuff like Deathbonnet Sprout // Deathbonnet Hulk and Urborg Lhurgoyf, and big five color human stuff like Jodah, the Uniifer, as well as a bunch more
Greninja (019/P-A) As a Stage 2 Pokmon, Greninja should make it through two evolutions (Froakie and Frogadier)