Let's take a look at Whisper, Blood Liturgist: Just recently, I played in a Masters 25 sealed event where the only match I lost was because of a card called Hells Caretaker
Crucially, that means you can attack immediately after you untap
Permission Blue already provides the best permission cards of any color in the game
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They each cost three, have 6 total power and toughness in 4s and 2s, they have one keyword and a tap ability that doesn't cost anything to use like mana or discards to drop your cost of their colors' spells by colorless at sorcery speed by either life lost or gained this turn
Turning your win condition into self-mill, however, gives us access to some powerful spells