About regular and alternative upgrades.

1. Hunters: They deal a lot of damage, plus invisibility will be very useful if you need to sneak up on an archer or a valuable enemy soldier. 2. Megeras: They deal more damage and run a little further. If you increase their speed with an artifact and tactics, they become a real monster, and the enemy won't be able to retaliate, avoiding losses. 3. Minotaur Gladiators: Constant morale (+1) allows this soldier to attack frequently, plus hitting twice per battle is a bit of a cheat, but it works. 4. Dark Riders: They have more defense and damage, they're like raiders... a bit underwhelming. 5. Poisonous Hydras: They regenerate twice as fast as cave hydras, and have more damage and defense. They also have 2 counterattacks, one with blood and one with heads. 6. Priestesses: A ranged unit in the army is always useful, and dark spells will also be helpful. 7. Black Dragon: There's not much to say here - damage, defense, and spell resistance are all good. Well... that's all.