Emerald/Steel Discard did have a previous iteration that found a place in the Into the Inklands meta for Disney Lorcana but it remains to be seen if it will return
Heaven Sent Heaven Sent provides you with an infinite stream of card draw! over time at about three mana per card This is maybe more of a riff on How to Keep an Izzet Mage Busy than anything else, but this card has a lot of potential in any Cube that can take advantage of incidental artifacts and/or cares about casting historic spells
Mulligans are not an exact science, and every situation you face will be slightly different
If you mostly want hits without clutter, storage costs, or postage, live ripping wins outright
Regular/Speed/Rush: The type of duel format (regular duel / speed duel / rush duel)
That gargantuan spike (an over-2,000 percent increase in price) pales in comparison to the Gengar, but that over-$200,000 price puts it in select company among Pikachu cards, with, seemingly, only the mythical Illustrator Pikachu card notching a sale price that high