Its speed-based cost reduction gets your vehicles out faster, and the stat buff it grants to your creatures helps to crew vehicles more efficiently
For standard play, it doesn't seem like its making any big rule expansions or overhauls, but the addition of plenty of new cards is still sure to shake up the meta in interesting ways
Well miracle is an alternate mana cost, so if you draw it as the first card of the turn, you can reveal it and cast it for free, and then use your spell for the turn to recast a keycard that was bounced or drop something from your hand
The front side here is, admittedly, pretty unexciting
Here is how the combo works: activate Duskmantle's ability, and tap Ghoulcaller's bell so each player mills 1 card