Perhaps, if you were curious what a tournament might be like, you might have checked out my article conveniently titled "Your First Tournament." You're all set
Rona, Herald of Invasion / Rona, Tolarian Obliterator Rona, Herald of Invasion can be very helpful in cycling through your deck, especially if youre running a lot of legendary cards
Cathars Crusade Cathars Crusade will make sure that all of your creatures enter the battlefield with +1/+1 counters
Malakir Rebirth / Malakir Mire Malakir Rebirth isnt an over-costed version of an existing card for a change, but it loses you life as you cast it
(Okay, it being a vanilla creature helped a lot.) The creative hinted at a Greek mythology-inspired world, so when we did that world, Theros , we made sure to include it