Something from the the newest set, which, right now, is Triumphant
Each character has a Strength value (how much damage they do in challenges), a Willpower value (how much damage they can take before being discarded), and a Lore value (how many points they give you when they quest)
Of those 50 or more, a minimum of five of the cards will be holographic and youll also get at least one GX, EX, Full Art, Tag Team, V, VMax or Secret Rare
With a transformed Defiant Thundermaw in play, you could also divert its two damage to other battle cards, snowballing the battle card transformations even further
If your deck's key engine is a 4cmc commander like Kaalia of the Vast, for example, then you will want to run ramp cards that can get her out faster, which means ramp that is between 0-2cmc so you can cast Kaalia on turn 3 or earlier instead of her usual turn 4
Choose your deck