Sol'kanar the Swamp King {2}{U}{B}{R}
Legendary Creature — Demon
Identity
Grixis
EDHREC rank
#20,016
Cheapest printing
US$0.24
TCGplayer
Printings
5
Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Whenever a player casts a black spell, you gain 1 life.
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.