Winter is a commander that can cheat out strong cards early if you're lucky enough to mill them
Black has the most forced sacrifice cards out of all the colors, making it a perfect commander for Sacrifice decks
You can include this as background for a deck with a succinct Voltron strategy looking to reduce life totals by combat damage like Alora, Merry Thief or Gut, True Soul Zealot
In Commander, all of the above goes double
Being able to steal your opponents spells is always good, and it opens up the possibility to cast basically anything you steal since you can play them by paying life instead of mana
You can make potentially huge tokens, remove artifacts and destroy enchantments, and for the finale, you can massively pump your creatures and give them trample