It also has the potential to serve as creature removal without killing your own Monastery Swiftspear
There's something to be said about never having to ink a card from your hand again, which is why the Legendary variant we mentioned earlier is also spiking at decent value since launch (sitting at around $26), but the Iconic rare is just on another planet
Theres usually a small entry fee that often includes a booster pack
Even if the caster has a weak board, Ruinous Ultimatum is still worth casting if they can't wait for another, cheaper board wipe
This seems great with things like Sneak Attack or other ways to cheat out huge creatures, leading to a kind of revolving door of huge creatures slamming out, getting sacrificed, big draws and dumping out other big creatures, then reanimating your sacrificed creatures, which seems fun