Miraculous Shine only costs one colorless energy, so one copy of Espeon-EX can be techd into any deck
Jace Beleren Jace Reawakened Jace, Arcane Strategist Jace, Architect of Thought Jace, Cunning Castaway Jace, Ingenious Mind-Mage Jace, Memory Adept Jace, Mirror Mage Jace, Telepath Unbound Jace, Unraveler of Secrets Jace, Wielder of Mysteries Jace, the Living Guildpact Jace, the Mind Sculptor Jace, the Perfected Mind Space Beleren
And in that scenario, this is strong
Journey Together combines cards from SV9 with additional cards not found in the Japanese set, creating a different card pool and pull rate structure
There's a couple of examples of this in the game design, and the main one is the Ink system
For example, creating three Rhystic Study copies makes it almost impossible for your opponents to play the game without feeding you cards, multiple Archangel of Tithes shuts down attackers, and so on