Wall of Denial If your plan is to swing with Defenders, Wall of Denial is one of the scariest: an 8-toughness, flying Defender that can't be targeted
While this will mostly be relevant in casual play, it's worth pointing out that if you have a Naban, Dean of Iteration on the battlefield, every Wizard that enters the battlefield will trigger Warstorm Surge, Fathom Mage, Angelic Chorus, and Purphoros, God of the Forge (among others) an additional time, which opens up an entirely different layer of deck-building potential that was missing with Panharmonicon, which only triggered abilities on artifacts and creatures
This means an extra land drop, another attack phase, and a whole new untap
Theyre inspiring me to get started tinkering with RotF as soon as I can, which is exactly what a starter deck is supposed to do
Another interesting aspect is that, although this is a 5-color commander, you can easily get away with building this deck with only a few colors, even none if you want