"Cubic Mandala" lets the controller target the opponent's destroyed monsters in the Graveyard that were sent there that turn and Special Summon them to the opponent's field, whilst reducing their ATK to 0 and placing a Cubic Counter on each
Albert's Dragoon form is also pretty decent as it allows you to wipe your opponent's monsters, although it would be really annoying if this did so while you had another Dragoon out to go for a lot of damage
Furthermore, they are the back of one of the best decks in the current format, Ryzeal
It wouldnt be my first pick for a dragon-themed deck, but it has some micro-synergies with the creature type and Ziatora is one of the best Jund commanders overall
For years the second card has been missing, either it was lost, or someone has it in their collection unknowingly, perhaps the news of these rare Pokemon cards finally selling for thousands could entice those to look in their basements and resurrect the missing Blastoise