Vanguard Controller
Vanguard Controllers were the chiefs of the spearhead forces of the Shadowlords, attacking various cities during the Summer of 2008 (see Vanguard).
They are humanoid riders on Dread Warhorses, and were fearsome opponents. They could cast Necromancer spells, and their weapons, known as Obsidian Blades, had an Armor Ignore attack that required no Mana. They wielded special kinds of Chaos Shields.
After a certain amount of damage was done to them, they (or their Warhorses depending on who you ask) could summon helpers, significant numbers of them. See Vanguard for more on the various creatures that could appear.
They would speak various Latin phrases, tell you to "Run!!!" and proclaim "We are Vanguard!!"