Ashnods Altar, Altar of Dementia, and the Eldrazi Monument give us three options for sacrificing creatures
It doesn't target any player, even if the spell mastery ability applies
Glin, Dwarf Emissary Lord of the Rings Glin, Dwarf Emissary is a very interesting Treasure-related commander, allowing us to sacrifice Treasures to goad creatures
You can pick an avatar from a selection of the games established characters, such as Jaya Ballard, Liliana Vess, or Teferi (so is somebody actually going to cast Idris Elba as Teferi, or?), but theres no attempt to depict you as a newbie planeswalker or something, aside from some slight interactions with named characters during the tutorial
There is a legal phrase called promissory estoppel, which essentially means that if your promise has serious repercussions for the other party and by not keeping it you caused some sort of harm (financial, in this casespoiler alert), youre liable for that harm and can be prosecuted
