If you're starting from zero, the best choice is a booster box or ETB from a modern set sold near MSRP with strong chase cards
Elspeth, Gideon, and Ajani are good planeswalkers to have among your creature-heavy decks, and good examples are Gideon Jura, Gideon, Ally of Zendikar, Elspeth, Knight-Errant, and Ajani, Adversary of Tyrants
Important things to note are that Yawgmoths Will does exile itself upon resolution, cast your spells with Threshold first, and to always make sure you leave enough instants/sorceries in your graveyard to enable spell mastery on Dark Petition
Bretagard Stronghold Suggested Cut : Forest Bretagard Stronghold enters the battlefield tapped, but it has a very relevant extra ability that this deck can make use of
A single Japanese booster pack is an affordable way to experience the difference firsthand