The Balrog of Moria {4}{B}{B}{R}
Legendary Creature — Avatar Demon
Identity
Rakdos
EDHREC rank
#4,751
Cheapest printing
US$0.70
TCGplayer
Printings
3
Trample, haste
When The Balrog of Moria dies, you may exile it. When you do, for each opponent, exile up to one target creature that player controls.
Cycling {3}{R} ({3}{R}, Discard this card: Draw a card.)
When you cycle this card, create two Treasure tokens.
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.