Urza, Lord High Artificer Though making a Construct token is arguably the least broken ability on Urza, Lord High Artificer, its enough token generation for it to score a spot on this list
Additional gameplay options are available under the settings menu, which you can access by tapping the cog wheel in the top right
Not because it is powerful, but because it shuts everything down
The bar is just so high on cards for so many decks above Bracket 2
By allowing it to target your own spells, you can suddenly build around the random element of this card and fill your deck to the brim with obnoxious expensive cards
This is different from Adventure from the Throne of Eldraine set, because you had a choice to cast either the creature or spell version