Discussion about Dungeon (Dark Elves).

Against Orcs, poison and cursed lands are only useful for reducing their rage, and the rest should be handled by the troops.

Yes, it will reduce the rage, but will there be much benefit from it? Against Orcs, summoning will be even better than Chaos, as the Orc army is fast and strong, and without a Phoenix to cover them when needed, you can be in trouble with Furies.
Vayshan is absolutely right; why complicate things with Dark Magic, searching for spells, and developing knowledge, when a Warlock is simply made for Chaos and summoning? I think a more interesting question is in which cases to develop which magic and how to use it...