I came up with this method myself, and I'm not very good at math, so it's possible that there is a more efficient way to find these probabilities
Right now on TCGPlayer, this card is valued at a market price of $16.24 USD
Identified by the retcons as a "Legendary Shapeshifter", Halfdane enters as a 3/3 before shifting into having the statline of another creature on the battlefield, represented here as he transforms to mimic that Viking guy
Varis thanked Playmaker for clearing his field, as he brought out "Twin Triangle Dragon" and revived "Cracking Dragon", at the cost of it unable to attack and 500 LP
Collecting the rarest cards can be fun, and each booster pack contains a mix of different rarities, with Enchanted cards being the most difficult to find