[Macros] How do I display a target name based on the what my target was?

[NocturniaUzuki]

It sounds like you are trying to put up Aspected Benefic as soon as it wears off.
But this isn't always the best idea.

No, but it often is, so it's useful to know when it's going to drop either way, so I know that the tank will effectively be taking more damage over time. I'm not going to cast Aspected Benefic when the tank's HP is dangerously low just because it runs out. But as far as general sustain goes, especially in easier dungeons, it's useful to just recast it and go back to DPSing. Oftentimes, the regen is all the tank needs to sustain.