Explore was a very popular mechanic in the original Ixalan block and naturally, it returned in The Lost Caverns of Ixalan and Lost Caverns of Ixalan Commander
Bartolom del Presidio Bartolom del Presidio doesnt offer much except efficiency, but that can be impactful
Instead, these cards should hopefully be a very welcome treat to anyone lucky enough to open one
Because paying X is part of the normal casting cost, paying an alternative cost for these cards will result in X=0 unless the alternative cost itself specifies a value for X, such as Lantern Flare or Disrupting Shoal
You just play it early, and its a potential threat for the rest of the game
To give you an idea of how good blue instants are compared to other colors, blue would have over 50% of a "Top 50 Instants of All Time" list (and take six of the top ten slots)