Aether Hub, Harnessed Lightning, Glint-Sleeve Siphoner, and Whirler Virtuoso are all fine energy-based cards that can be played outside of a true energy sub-theme
While a prize pack Radiant Zard may be technically worth more than another card, like @magikarp ex was saying, it may be relatively impossible to sell at that market price. @SilverShady was just saying that they would be willing to buy onejust not for that price
Its worth making the effort to draft any dual lands that can tap for at least one of your main colors, since at bare minimum it upgrades Artillery Blast into bargain removal
Rakdos Madness: My worry here is that madness cards just aren't that powerful, and the Rakdos Madness deck has a bunch of them
The Master of Keys The Master of Keys is a cellarspawn who is able to use the House's doors as thresholds not just between adjacent rooms but unconnected rooms as well
A risky, dangerous dungeon that promises great power