You're basically gifting your opponents dangerous loose cannons that turn the battlefield into a nonstop slugfest they can't control
A card that can destroy artifacts or enchantments as an option on part of the card then it gains a decent amount of value in cube
Cards that require you to pay mana (except for the categories of "Attack Taxers" and "Complete Combat Protection"), pay more than 3 life,discard a card, or sacrifice a creature per round to be effective
What have their findings been
Bolas is ancient, wise, selfish, and aggressive at times
Each Set Booster contains 12 Magic cards, 1 Art Card (includes a D&D monster stat block on the back in 33% of packs), and 1 token, ad card, or special card from Magic's history (a card from "The List")