Arcanist getting rooted while using Pragmatic Fatecraver

RexyCat

I have had issue in West Weald where my Arcanist suddenly are getting rooted (not from CC) and I can't move at all while fighting WB or Daily Mirror bosses in event. Normally you should be able to keep channel while moving, but when this happens character will channel, but be unresponsive for movement, so you can't avoid getting hit or interrupt your channel.