This is Jerian, the Dreadnought. Everybody say "Hi, Jerian!". As so often, he's got several weapon arms for switching gear.
Fun fact on the side - this was the first time I actually built a plastic Dreadnought. Here are some pictures of the sides with various arms:
I'm currently working on a nice banner for him so stay tuned! (No idea what GW thought with not putting a proper banner with that kit).