Magnus looks pissed off. If I had to take a guess it's probably be because he has to stand next to mortarion, who is visibly radiating green shit everywhere. As well as angron, who is probably screeching about some metal band with the words 'nail' and 'gore' in the name.
Meanwhile Horus and Fulgrim discuss techniques to shining their heads.
Khan stands like a smug fucker, thinking about his motorbike probably.