I can see how and why that would be useful, but Im not seeing the type of deck that really wants to play this right now
This combo needs 3 cards: Heartstone + Basalt Monolith + Karn, the Great Creator
This white 'walker makes tokens and gains life, which is everything that Trostani is about
As long as an opponent controls more lands than you, you may play lands from the top of your library
Its owner will only have to pay two mana, which is pretty low for something that could obliterate the opponent in 5 turns, but its highly unlikely that youll get the desired outcome out of five coin tosses in a row, considering how theyre meant to be 50/50
Notably, Yanmega ex only uses Colourless Energy and must discard one upon attacking, which is where Dialga ex's Metallic Turbo - an attack that puts two Steel Energy on any Benched Pokemon - comes in good use