Regrettably (since I want the game to improve so I can keep playing it and have fun) I completely agree with @Arelana and @Aelthwyn. Very disappointing answers that unfortunately were along the lines as was already expected.
Every day it is becoming more clear that the game has grown so much (too much!) that the devs that make the design choices simply don’t have the time to play anymore. There are many things illustrating this sad observation, of which Wisp is the most glaringly obvious one.
Remember, three weeks ago the devs thought removing mana surges from 4-matches would solve the issue of Wisp filling so fast…
But Wisp is fast and requires only 9 mana to fill, which means it starts at six mana. That means a single 3-match on the AI’s first turn would fill Wisp (and since Wisp is virtually always used in pairs, a mana surge on that single 3-mtach would fill both Wisps)… No 4-match required here. 
Now if the devs actually played the game they’d know this, but the evidence obviously shows they don’t know. Only logical conclusion is that they don’t play anymore, meaning they have no clue as to what is OP, besides the “most used defense troop” stat. Which I will admit is useful for them, but it doesn’t tell the whole story. Only playing the game can tell you the whole story…