Jo Grant

Each historic card in your hand has cycling {2}{W}. ({2}{W}, Discard that card: Draw a card.)
Whenever you cycle a card, put a +1/+1 counter on Jo Grant.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Gavi, Nest Warden

You may pay {0} rather than pay the cycling cost of the first card you cycle each turn.
Whenever you draw your second card each turn, create a 2/2 red and white Dinosaur Cat creature token.

The Fifteenth Doctor

When The Fifteenth Doctor enters the battlefield or attacks, mill three cards. You may put an artifact card with mana value 2 or 3 from among them into your hand.
The first nonartifact spell you cast each turn has improvise. (Your artifacts can help cast that spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)