While Underworld Breach has the downside of giving your cards Escape 3 (and causing you to blow up your graveyard in the meantime), it also has the incredibly relevant effect of not exiling the card that youre casting
This gives [c]Galvanic Relay[/c] a higher potential upside than [c]Act on Impulse[/c], as you can chain spells like [c]Pyretic Ritual[/c] and [c]Manamorphose[/c] to boost up your storm count, that way youll have plenty of cards to play for your next turn
Every change it suggests is a proposal you explicitly approve or skip and every action is reversible so you stay in control
Colors can differ a bit of the original thanks to different (monitor) screens and the printing
Sangan, Witch of the Black Forest ) become completely useless
As Emchompite explains, Japanese booster boxes have predetermined hit rates, so the population of cards is higher and overall "rarity" of cards is lower