It may seem counter-intuitive to many people that a type of booster pack is sold for a collectible card game that isnt necessarily intended for play, but Collector Booster packs are intended to provide the best looking selection of cards in any given pack and may be just used for bragging rights, instead of being handled and shuffled in actual decks, during fraught games of MTG
Taigam, Ojutai Master was a new card printed for the The Ur-Dragon precon
Flip a coin
Cards that "represent negative play patterns and interactions that you generally shouldn't spring on unsuspecting opponents", and which would probably be banned if uncards were made legal
EDHRec.com is an excellent source for Commander info and can give you ideas on how to build your next Commander deck or tune an existing one
When you limit players to just one noncreature spell per turn, it throws a wrench in the plans of decks like Storm, Living End, or even niche decks like Jeskai Ascendancy