Heres a few addons I came across for the malygos encounter. Now I dont think they are outright needed, but that may prove to be helpful for some people:
Malygos Helper (http://wow.curse.com/downloads/wow-addons/details/malygos-helper.aspx) - Monitors monitor the dot stacking and combos of the raid with 1 Bar per person, with their name and dot stack. Bars will fade off as their dot expires.
Engulf (http://wow.curse.com/downloads/wow-addons/details/engulf.aspx) - Engulf is a simple timer addon to display your Engulf in Flames debuff duration during the Malygos encounter.
MalygosCP (http://www.wowinterface.com/downloads/info12145-MalygosCP.html) - Addon that keeps track of the Energy, combo points and the Engulf in Flames on Malygos.