Underworld Breach has powered some of the strongest combo turns in recent years, which is why it ended up banned in multiple formats
There is no clear distinction between a straight edge and a wavy edge
Do the sum first: if a gem-mint result would not comfortably beat the service charge plus postage, leave the card raw and enjoy it as it is
Open a Mythic Rare Wildcard, redeem it for any mythic rare card in-game
Sapphire continues the trend from Rise Of The Floodborn of showing how powerful synergy between characters can be with Huey, Dewy, and Louie, particularly with Huey's ability, Three Nephews, which allows you to draw three cards if one of each of the Nephews is on the field
I also like three-mana rocks and land fetch spells, because they tend to be more versatile