April O'Neil, Human Element {3}{U}
Legendary Creature — Human Detective
BlueCommander: legal
Identity
Blue
EDHREC rank
#12,161
Cheapest printing
US$3.46
TCGplayer
Printings
1
Whenever a player casts an artifact, instant, or sorcery spell, you create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")
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.