Choose Link Trade (3rd option in the list, under Tera Raid Battle) and then Set Link Code
Most of them aren't much to write home about, and then you have Fable of the Mirror-Breaker, which also broke multiple formats
Supreme Verdict (67 copies) When its time to reset the board, Supreme Verdict is one of the best options
What makes this card so sought-after is that you will only find it as a Quarter Century Secret Rare
Reach for the Sky for me is a bit too expensive, the effect is powerful and will certainly generate blow out scenarios, but the downside of a 4 mana combat trick is that if your opponent has instant speed removal, you are in trouble and often end up with bad trades
As a Mega Evolution Pokemon, it boasts high HP and the ability to deliver powerful attacks capable of quickly overwhelming opponents