Here's the card you'll need to find 99 times for 'Gimmighoul Collection': x99 Gimmighoul #36 (One Diamond) Reward: Gholdengo Emblem
While some are fairly common, like ones that come with a magazine, clothes, like the Pikachu Illustrator card or the Magikarp Tamamushi University Promo Card, are incredibly rare
Then use Rift Summoner to break that demon (since it was going to break anyway) to get 2 more demons
First-edition cards are the most coveted by collectors, and even common and uncommon first-edition cards can fetch a decent price online
And dont forget to visit the official Draftsim Discord where you can find and join an amazing community of MTG fans
Using extra ink to move your characters to Motunui before sacrificing them in a challenge is also a great strategy, since every one of your characters that's banished there will move to your inkwell instead of your discard pile