It says the offer is aimed at metagamers who've found the MTG Arena decks online and "just want their cards quickly so they can start playing their deck." If you want to get the most out of MTG Arena, you'll want the free packs, XP, cosmetics, and goodies you can nab with all the MTG Arena codes.
As with their predecessors, new events are triggered when certain conditions are met, but this time entire creatures like a Shiva summon can evolve and change as a result
Just casting a Mulldrifter for full value was fun, and now we even get a couple extra life
Making room for new cards
It was the first major, on-curve creature with a powerful ability to boot (compared to other cards of a similar cost, like Nettletooth Djinn, that had weaknesses instead)
Abyssal Persecutor makes it so that you cant win the game and your opponents cant lose (but at least you get a 6/6 body in the meanwhile)