There are multiple ways of doing this achievement through "juggling" enemies with your manipulation/force spells and the use of battle arenas.
I stumbled across a group of Ashwinders fighting a troll (not too uncommon, especially if you are hunting Collection boxes within bandit camps) and managed to earn this achievement by spamming my general attack and dodge-rolling any incoming damage.
Keep in mind using "flipendo" on a troll's forward slam will smash his club into his face and stun him, an easy way to create more distance between you and rack up a few extra hits.
My only other tip would be to try and earn this earlier in the game, as trolls die pretty easy once you're level 30 or above.