Mitsuko is amazing. She’s sturdy and in a class where many don’t have other options (since so many Sorcerers are behind the paywall). I’ve spent some and my options are basically Mitsuko, Sabina (who I don’t even use in wars), and…whoever the three star Sorcerers are. As a result, I took Mitsuko to +11 or something and am now holding ~700 emblems hoping to land Ursena or a season 3 sorcerer.
She destroys blue heroes who are average speed or slower at flank and any speed wing. She’s impactful enough that I roll the dice with her against Telluria’s flanked by Vela (though I may not being a ton of other reds in that situation). Also, she does a lot against the Finley, GM, T, V, whoever defense.
One major benefit is that she allows you to stack against a green tank or flank while also crushing the blue hero - it’s like you get an extra stack on the field, conceptually.
I’ve heard many say she’s a niche hero, but she’s absurdly good at that niche and that niche is hardly small - I mean, there’s always a blue hero on the field.
Lastly, I’m writing this having only recently gotten my red mana troop to level 23; she’s now markedly better.