An interesting idea, but I can see two problems:

1. Something that requires full lilies won't work unless the entire lily mechanic is reworked (as it should TBH). WHM has too many abilities that consume lilies and too little incentive to use abilities that generate lilies. It would require planning and preparation to have a full three lilies up at the time Reverse is needed.

2. It's extremely dangerous in content with multiple healers. If the other healer isn't paying constant attention to this specific thing they can very easily end up killing the target Reverse was supposed to save. With the amount of other things also requiring attention slip-ups will likely happen more often than not.