In a quest, we saw that he used his powers to trap the Abyssal Herald using force. Now, in the game, the same element in the game doesn't react with each other. I mean that if you apply a Pyro element to a Pyro slime, the slime won't take any damage. But that contradicts that Dainsleif has pure Abyss powers. Even his name was "Twilight Sword," roughly translating to a neutral state. Now we have white light from which all sorts of colors can be derived, and the opposite of it can be dark powers, meaning the Abyss power. Going by that theory, if Dainsleif used his opposite powers, he could Grab the Abyss Herald while it was escaping one time from the battlefield. And, when the Abyss Herald left through a portal, Dainleif dashed to the portal and was faster than the Traveler. It can mean that we may see him using a dash-like skill just like Yelan has on her. Though, I don't have any clue what his elemental burst might be. That's all I can think of now after watching a ton of theory videos and lore crumbs from the game. But, in actuality, only time will tell how the events will unfold in the game.