Esior, Wardwing Familiar {1}{U}
Legendary Creature — Bird
BlueCommander: legal
Identity
Blue
EDHREC rank
#3,433
Cheapest printing
US$0.51
TCGplayer
Printings
2
Flying
Spells your opponents cast that target one or more commanders you control cost {3} more to cast.
Partner (You can have two commanders if both have partner.)
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.