The preview cards feature some old Magic mechanics that will be returning to competitive formats with the ATLA set, including the Lesson spell subtype, Shrine and Ally creature subtype, and double-faced Saga cards that transform into powerful permanents
Previously, there was a ruling that when Welder was played and an energy attached, the next step of drawing cards could be interrupted by an effect such as Eevees Ability Energy Evolution
Add 1 Battleguard Rage or Battleguard Howling from your deck to your hand
Then go through victory road
Where Unpredictable Cycling has cards like Polymorph and Possibility Storm beat is that it is also a very solid fair card
(10/7/2022) If you activate a card's unearth ability but that card is removed from your graveyard before the ability resolves, that unearth ability will resolve and do nothing