While adventure-supporting Commanders already exist pre-Wilds of Eldraine, Beluna is the first Commander to be an adventure herself
Oh, and of course Sol Ring and Swords to Plowshares are coming too, but with stunning Stardew Valley art
For example, Ley Druid targets lands while Fyndhorn Brownie untaps a creature (and, yes, I chose that card as an example because of the sweet art!)
On top of that, he drains opponents whenever any creature dies, and once that drain trigger has resolved four times in a turn, he transforms into Sephiroth, One-Winged Angel
You can read about Ari Laxs adventures with the archetype here and even watch him play it here
but no matter how you name it, it is guidelines that come from statistics from regular plays