Koh, the Face Stealer {4}{B}{B}
Legendary Creature — Shapeshifter Spirit
BlackCommander: legal
Identity
Black
EDHREC rank
#9,450
Cheapest printing
US$0.37
TCGplayer
Printings
3
When Koh enters, exile up to one other target creature.
Whenever another nontoken creature dies, you may exile it.
Pay 1 life: Choose a creature card exiled with Koh.
Koh has all activated and triggered abilities of the last chosen card.
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.