Final Fantasy TCG Opus XV (15) Crystal Dominion Booster Box The Crystal reaches its apex in our latest Opus! Use abilities and more to gain “Crystals,” and experience yet another layer of strategy in FFTCG! Dice or counters can be used to keep track of the number of Crystals, but Crystal Dominion will also include two kinds of premium version Crystal cards, and these can also be used during games! Features Legacy Cards. Legacy cards appear once again in this set, with particularly popular cards from past sets included as premium full art cards.