Human

Doctor spells you cast cost {1} less to cast.

Foundations Tokens

Bloomburrow Commander Tokens

Murders at Karlov Manor Tokens

Doctor Who Tokens

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

The Eleventh Hour

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Search your library for a Doctor card, reveal it, put it into your hand, then shuffle.
II — Create a Food token and a 1/1 white Human creature token with "Doctor spells you cast cost {1} less to cast."
III — Create a token that's a copy of target creature, except it's a legendary Alien named Prisoner Zero.