Romana II {3}{W}
Legendary Creature — Time Lord Scientist
WhiteCommander: legal
Identity
White
EDHREC rank
#15,834
Cheapest printing
US$0.26
TCGplayer
Printings
4
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.)
Keywords: vigilance, doctor's companion
Every printing
highest TCGplayer market first; a card with only a thin single listing shows its low
In short
A Commander deck is a commander and 99 other cards, one copy of each (except basic lands), all inside the commander's colour identity. Paste a full list into the deck price calculator to price it and check it against the format.