Underworld Breach has powered some of the strongest combo turns in recent years, which is why it ended up banned in multiple formats
In combination with Cavern Harpy, Baleful Strix, and Ice-Fang Coatl, you have a potent combination that draws numerous cards at instant speed
Within a few weeks, we moved around the bouncing of creatures from a plus ability to a minus ability and pulled back the third ability to match up with Brainstorm (and moved it up to the second ability and turned it into a 0)
Plus, if you put a Holy Armor on it, it was a 2/3 or a Holy Strength which would make it a 3/3 and those could both be cast on it before you attacked with it on your second turn
I feel like it should be fairly easy to achieve the citys blessing on Turn 5 or 6, and so Tilonallis Summoner will create an army of 1/1 red Elemental creature tokens that are quite ready and willing to carry the banner for Marton