Card flow on spell chains: Whirlwind of Thought, Tome of the Guildpact, Expressive Iteration, Guided Passage, Urban Evolution, Escape to the Wilds
(Or save it for later!) When a Vault is opened, it will award: One rare Wildcard Two uncommon Wildcards One mythic rare Individual Card Reward One rare Individual Card Reward One uncommon Individual Card Reward Combine that with the daily gold and card rewards, plus the weekly pack rewards, and you should be able to expand your collection fairly quickly
Feral Hydra enters the battlefield with X +1/+1 counters on it
Moving lore counters between summons is a nice synergy as well, because you can keep powerful sagas around while accelerating another ones chapter progression
Rarity & Collectible Appeal Cards from the Pokmon TCG: 151 expansion and the Blooming Waters promos feature a wide rarity spectrum: Common & Uncommon Rare Double Rare Ultra Rare Illustration Rare Special Illustration Rare Secret Rare This rarity structure ensures excitement for pack openings while maintaining strong long-term collector value