Halo foil ghostfire cards will only appear one percent of the time, making the pull rates incredibly low
Obviously, you dont really want to give up a real creature for the effect all the time, otherwise it is a roundabout way of rummaging, but recurring removal spells is especially potent, and giving up a creature for that is often going to be worth it, especially if you sacrifice a card that brings you some value when it dies
Elspeth, Storm Slayer This 5-drop mono-White planeswalker has 5 loyalty and then doubles your token-making with a Parallel Lives static ability
Thats a strong and compelling ability for a card with also powerful stats
Admittedly, tapping one creature in each of the first two chapters is considerably less good in Commander
In the case of equipping one mana artifact equipment and redeeming mutagen tokens, those would then be free