Horus called out Malcador for erasing the Two Missing Primarchs, as Horus was furious about what was done to his brothers. Malcador used his powers to choke Horus yet Horus gritted his teeth and bared it. Jaghatai and Alpharius looked on in horror at it all.
The lower half of the pic is Horus holding Eugen Temba, after the latter was corrupted by Nurgle and tried to kill the Warmaster. The two were good friends.
We can say Nurgle is the very first Chaos god introduced in the series. Also, Temba is the one who wounded Horus, after which he got "healed" by the Serpent's Lodge and the galaxy burned.
