Some cards have abilities that trigger whenever a player "faces a dilemma," which happens whenever that player chooses one or more modes for a spell or ability
It's super flexible, as you can use it when your own horde swings in, or when another player goes in on the offensive (they don't even have to be sending everything/anything at you.) However, while I can see this card working pretty well in any blue/white/green tokens deck, it's obviously best with an MTG commander that cares about birds
It also looks fairly delicious too don't you think
Articuno ex serves as a strong substitution if Starmie ex has taken significant damage
It's an excellent infect commander, or for superfriends, or +1/+1 counters, and as the best proliferate commander in the game, Atraxa is one of your best choices for any of these themes