The original question was an inquiry about WARRIOR ONLY attacking, so naturally there would be no other troop type included in the information I posted. Those numbers are from personal experience, since I do not use any other type of army except for warriors.

For NPC cities, attacking them with warriors only, you will sustain losses that become quite substantial the higher the level of the NPC city you're attacking. The figures I put in may be slightly on the overkill side for certain levels, but those are for guaranteed wins with the attacks.

EDIT to my original figures: It's 80,000 for a Level 8 NPC city, and Level 9 *can* be successfully attacked with 90k warriors, but you'd really want to send about 15k to 25k more to ensure victory with the battle.

As for quantity of losses ~ for an NPC city that is Level 3 or higher, using the troop quantities that I indicated, you will lose troops numbering in the thousands. At Level 5 and higher, these numbers will be in the tens of thousands, to the point where you will lose over half your army.

Warrior only attacks on NPC cities will give you the largest possible amount of prestige for the attack, and will also give your lead hero the most possible amount of experience. (Example ~ On a fully regenerated Level 8 NPC city with a warrior only attack, you can get over 2,000 prestige and your hero can get over 600,000 experience.)