Well…to say that a Level 250 elite tier monster is strong…would be circumstantial. At most, their DPS level would be as only around 70,000. Based on their damage, they would not be a match to a Level 250 player with a full Ethereal gear. On the other hand, when fighting a boss, the ability to deal high damage and ANY damage at all would make all the difference in determining the victor.
As mentioned, Kenzack's {Void Blast} was an AoE powerful skill. Those without Transformations could not come close to the boss. Even with super-powered attacks, one would die without the ability to take several hits from that.
Elite monsters were different. Their HP would be as high as 125,000,000. They would last for as long as 3 minutes without healing while fighting the boss.
Hence, the ultimate rule of war: Only the living can be useful!