The first example we saw was Barbarian Class, which is a one-mana Red enchantment that effectively gives you advantage on your dice rolls, so you can roll two dice and then pick the higher of the two
It's quite mathy, but he goes into a great deal of detail and explains his rationale, while not ignoring the realities of the game (there are one-mana Cycling cards, cards that fetch lands, cards that tap to add mana which aren't lands, and more.)
Factor in additional deckbuilding potential due to Jeska's Partner ability and you have a great red commander option
Preston, the Vanisher Flicker effects are the best enabler for Preston, the Vanishers powerful ability
Shivan Dragon
Some spells require additional choices to be made or targets to be chosen in the event the Gift is given