Currently upgrades are somewhat limited in the Energy design space, but this is due to change later in 2024 so this may get much better
When used alongside a card that lets you reshuffle your graveyard back into your deck, Time Walk can still be quite the strong card, and that means its a highly sought-after one, too
The real creepy implication here, in my mind, is the lore of a Planeswalker using some real shady necromantic magic to bring creatures back to life straight from the graveyard
Learn is a keyword action that lets you either discard a card and draw a card or put a Lesson card from outside the game into your hand.
Lastly, theres Amnesia, the closing act
Driven by grief he seeks revenge against the Empire and joins the game's roster of playable characters