The strength of the Dungeon lies in everything:) Since each warrior in the Warlock's army, at a high level of development, is capable of inflicting additional damage comparable to the effect of two Earth Shock spells (let's say, if your hero has already passed the 20-level mark). Judge for yourself.
In reality, it's not that great.
I myself really enjoy playing as Dark Elves, but even though it's irresistible, it still doesn't allow a Warlock unit to inflict damage equal to 2 Earth Shocks, unless it's Earth Shocks cast by someone like Laslo with a spell power of 1:)
Yes, and summoning is indeed the Dark Elves' forte.