If you hit a strong establishing champion when you play this, and you used Mist Guide Herald as an establishing champion, it is better than just playing that establishing champion
Do you play a big monster in attack position to intimidate your opponent, or play it safe with a defense position monster, to protect those life points
This creature not only makes your instant and sorcery spells cost one less to cast, but by sacrificing it you can copy the next instant or sorcery spell you cast that turn - and not just once, but for each time you've cast your Commander from the command zone in that game
Are you trying to build up your stuff and keep it in play
Playing four colours in constructed could be taxing, as you would have to spread your colours wide with multiple Snow Dual Lands
It's also way easier to scale up than landfall