#showtooltip
/cast [known:378773,@mouseover,harm,nodead][known:378773,harm] Greater Purge; [@mouseover,harm,nodead][harm] Purge
That’s from one of the stickies, with the purify stuff taken out.
TBH I don’t know from Shamans, so I am uncertain whether it works, but it looks how a macro is supposed to look generally.