mtg exile cards from the top of your library until Jodah, Unifier (PDMU) #203p Wrenn's Resolve

(And if you're still learning, even better, as MTG Arena is excellent for new players!) They have Sealed events starting June 25, and the play experience is still the same, great Magic

Valakut Awakening / Valakut Stoneforge Valakut Awakening is another combo piece, or at least something that can help you get there

In the early game it's just a five-mana Damnation, and in the mid-game it's an okay sweeper with a few dorks, later you can play around it and really push the board your direction

LaughingPlace.com

If your Commander costs four mana, then this will likely be a fair mana spent to give a +4/+4 boost and this fits