Posted this in the other Wisp thread:
I’ve found this to work for green day, no losses to a wisps yet.
Queen Ysabelle
Forest Guardian
Ketras the Bull
Queen Aurora
Use Ketras’ first cast on slot three as this will kill that troop (certainly if you’ve buffed him with QY or QA) and soften the second Wisp. The first Wisp gets softened and kill by QY and skulls to the face, second Wisp should die quick to skulls.
One shot the last troop with Ketras of full a again.
I use Talon banner and rush Forest Guardian. Normally on turn two I’ve got a full FG that will get enough skulls onto the board to kill first Wisp and greens to fill QY.
Shameless link: 
GW - Wisp counters for each color: