Not only is the Flamecaller the only non-Pyromaster version of the Walker good enough to make the cut in a lot of decks, but she can really enjoy being added to control builds
Assuming you used Red-Eyes Black Dragon as material for the XYZ summon, this effect allows you to bring back a 2,400-attack-point Monster immediately after Special Summoning Flare Metal Dragon
These cards also tend to belong to sets that aren't legal in competitive formats, which means that they are bought strictly for collection purposes, rather than having any actual use in the game
Other notable Dominaria Remastered cards: Mystic Remora - $9 Time Stretch- $22 Dark Depths - $18 Entomb - $20 Arboria - $20
With that loop in place, you can replay Strip Mine every turn to gradually dismantle an opponents mana base until casting spells is no longer an option
They're decently statted for their costs, too, so making sure you have a few of them in your opening hand is paramount