For my tastes, as guidelines I think are worth sticking to, a keyword mechanic needs to be doing offloading in the rules text that makes things more convenient , it needs to have human-understandable reminder text that isnt just the rules text written out, and it needs to be something that other things can usefully reference
What's particularly interesting for this is that it triggers off any card type, not just creatures
However, thanks to a mistake, the printing of this card says that Koma's ability only activates on its owner's upkeep, making the creature far less powerful
Especially since they sport an Esper color identity, allowing you access to all manner of white spells
Each film in the Millenium series is a self contained storyline
No one can try to destroy the creature you sacrificed to prevent you from casting this spell