Transforming versions of villains was a great option for rares and mythic rares, but it was important to have something to feel villainous at lower rarities
8 Capital Punishment Capital Punishment is a six-mana black sorcery that lets you deal with enemy resources
Aang and La, Ocean's Fury Legendary Creature Avatar Spirit Ally Reach, trample Whenever Aang and La attack, put a +1/+1 counter on each tapped creature you control
You play strong characters, you banish your opponents' characters, and when you don't see any big threats on their side of the board, you start questing
MTG Arena will offer you starter decks, and you could always purchase planeswalker decks for the paper version, but nothing beats the feeling of taking something you built and dominating the competition with it