Opal Palace is a common Land card from Commander Legends (CMR), collector number 707. Current market price: $1.50 (foil $3.59), TCGplayer market prices via Scryfall.
{T}: Add {C}. {1}, {T}: Add one mana of any color in your commander's color identity. If you spend this mana to cast your commander, it enters with a number of additional +1/+1 counters on it equal to the number of times it's been cast from the command zone this game.