There seems to be a lot of hate about her that is undeserving. I do agree that unless you plan to go Green tanks for war she should probably not end up on your defense. She does a lot less when in a flank than as a tank… BUT with that said she is still very useful and a 5* healer with plenty of utility:
Incorrect for many of the raids in Diamond. Melendor is serviceable, but often gets one/two shot (any sniper, Odin/Frigg, <“Insert Ninja Here”>). I do use Melendor rarely when I NEED a dispel like a Krampus/Taunt/Riposte, but in every other case the minion plus the HoT is more effective life immediately and enough over time that her utility and survivability outmatch any Melendor. Remember, she has 5* stats and can take plenty of hits.
Again, she is a healer/support. Do not forget her mana effect can set you ahead a turn or two before the defense goes off. The damage could not even exist and I would still bring her over a 4* healer as the 5* survivability is key in Diamond over anything else. Her minions give a ~200HP boost and the heal over time while not amazing added together keeps me alive much more than C Melendor. Having to wait a turn for HP to tick is sometimes too little too late.
As for the original question:
Do you think you need a beefy green healer/support for raids/war/tournaments/events? If so then I think she does a great job as just that. Just makes my C.Melendor warm the bench more often than not, as I do not always need a second dispel with Evelyn around too.
P.S. Minions get around the “Bloody” rules and give you hp where other healers cannot. She’s still a gem even if she is not a bright as they originally made her.