Tyukina Tatiana

"Where now the horse and the rider?
Where is the horn that was blowing?
Where is the helm and the hauberk,
and the bright hair flowing?"
—Lament for the Rohirrim

Esquire of the King

{4}{W}, {T}: Creatures you control get +1/+1 until end of turn. This ability costs {2} less to activate if you control a legendary creature.

Romana II

Vigilance
{1}, {T}: Create a tapped token that's a copy of target token that entered this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Graham O'Brien

Paradox — Whenever you cast a spell from anywhere other than your hand, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Doctor's companion (You can have two commanders if the other is the Doctor.)

"The most damning is still to come. And when I have finished, this court will demand your life!"

The Valeyard

If an opponent would face a villainous choice, they face that choice an additional time. (They can make the same or different choices.)
While voting, you may vote an additional time.

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Human

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