I have had a long struggle with chaos spawn and their attack patterns, with their grabs and swipes being the bane of my existence. While the general idea is dodging backwards to avoid them, I found it is easy to get backed into a wall or corner due to their aggressive flurries. If you are too close to them and have a low dodge range then it will also be impossible to dodge far enough back to avoid the grab.
It seems like dodging left and away from their tentacle arm can often save you from being grabbed or hit. Dodging left can also just be a good general practice with them as they are less likely to flurry and instead stay in place for your allies to attack, although they will need to actively keep behind him.