Gandalf, Westward Voyager {3}{G}{U}
Legendary Creature — Avatar Wizard
Identity
Simic
EDHREC rank
#13,144
Cheapest printing
US$0.29
TCGplayer
Printings
3
Whenever you cast a spell with mana value 5 or greater, each opponent reveals the top card of their library. If any of those cards shares a card type with that spell, copy that spell, you may choose new targets for the copy, and each opponent draws a card. Otherwise, you draw a card. (A copy of a permanent spell becomes a token.)
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.