Necromancy in Heroes 4

Basic Necromancy gives the hero the ability to raise a number of skeletons equal to 10% of the strength of a defeated army, as long as that number doesn't exceed 40 experience points of undead, plus 10% per level of the hero. Also, the hero can create only 1 undead creature per slain enemy. Undead, mechanical, and elemental creatures cannot be raised.

Advanced Necromancy gives the hero the ability to raise a number of skeletons equal to 15% of the strength of a defeated army, as long as that number doesn't exceed 80 experience points of undead, plus 10% per level of the hero. Also, the hero can create only 1 undead creature per slain enemy. Undead, mechanical, and elemental creatures cannot be raised.

Expert Necromancy gives the hero the ability to raise a number of skeletons or ghosts equal to 20% of the strength of a defeated army, as long as that number doesn't exceed 120 experience points of undead, plus 10% per level of the hero. Also, the hero can create only 1 undead creature per slain enemy. Undead, mechanical, and elemental creatures cannot be raised.

Master Necromancy gives the hero the ability to raise a number of skeletons or ghosts equal to 25% of the strength of a defeated army, as long as that number doesn't exceed 160 experience points of undead, plus 10% per level of the hero. Also, the hero can create only 1 undead creature per slain enemy. Undead, mechanical, and elemental creatures cannot be raised.

Grandmaster Necromancy gives the hero the ability to raise a number of skeletons, ghosts, or vampires equal to 30% of the strength of a defeated army, as long as that number doesn't exceed 200 experience points of undead, plus 10% per level of the hero. The hero can create only 1 undead creature per slain enemy. Undead, mechanical, and elemental creatures cannot be raised.