The black dragonspawn Wyrmthalak oversees the lower spire's forces as they prepare for their assault against the dwarves. He has no love for the false Horde or its brutish members, and he will sacrifice any number of Blackhand's minions to protect his master, Nefarian.
Cleave — Inflicts 110% of normal melee damage to an enemy and its nearest allies, affecting up to 3 targets in a 180 degree arc.
Snap Kick — Bloodaxe Veterans kick a player, inflicting Physical damage and stunning them for 2 sec.
Pummel — Bloodaxe Veterans pummel a player, inflicting Physical damage and interrupting their spell being cast for 4 sec.
Wyrmthalak is a relatively simple fight. He performs a knockback so it is best to tank him against the wall behind him. Melee DPS should stand behind Wyrmthalak to avoid the Cleave and Slam abilities. When he reaches around 50% health, two random choices of a Spirestone Warlord, Smolderthorn Berserker, or Bloodaxe Veteran will run up the ramp to assist him. They will need to be controlled or off-tanked to prevent them from attacking casters.
If you can kill Wyrmthalak fast enough, move back to the wall behind where Wyrmthalak was initially standing. The two mobs that show up to help, which if Wyrmthalak is already dead, will just stand there and do nothing and you won't aggro them.
Wyrmthalak is soloable with most level 70 classes.