Hero choice
For this BOSS, if you happen to have a troll hero in your hand, the whole battle will become very simple, but if not, I recommend the alchemist as a hero here. As far as positive ability is concerned, he may be one of the few heroes who can fight in World War I. His active skills have strong abnormal recovery ability and his own blood volume is also sufficient. It's up to him to play hardball!
Array method
Pay attention to the arrangement. Although you can hold the steel in the front row of alchemy, the more you drag it to the later stage, the greater your pressure will become with the release of enemy skills in the back row, so the output in the back row must keep up, so that you can kill the troll in a short time without losing the hero.