Fan Flower does looks good.
Lvl 90 of castle (with a purple and two neutral pests) was the main thing I used Vervain for along with Onci bride, but my big damage girl on that team was Iwarenge which is single target like Fan Flower is. It was a real pain in the rear waiting for RNG to deliver a victory over the purple pest first which had to be done to win it. 2 outta 3 times no workie
I really want Verbascum so I never have to deal with that again. maybe they will make something similar in RG later.