Opal Palace is a common Land card from Commander 2016 (C16), collector number 312. Current market price: $0.48, 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.