Kingdom Rush Wiki:Reference page

General Facts

All magic resistant enemies receive less damage from Mages,
All armored enemies received less damage from Barracks, archers, and artilleries.
Artillery ignores 1/2 of armor.
Only archers and mages can deal with flying enemies, as well as ranged allies and heroes. Artillery can him them with splash damage when targeting ground enemies. The falling meteors from a Rain of Fire can also damage them.
True Damage ignores armor and magic resistance, so rely on HP.
Artillery cannot damage enemies with physical immunity (except in Kingdom Rush: Vengeance).
Immune resistance is not the same thing as a 100% resistance, therefore it cannot be written as a percentage.
Damage from towers, enemies, allies, etc. are computerized between two sets of numbers (highest damage and lowest damage).
Increment of damage, armor, and health on endless levels start from the wave they spawn and increases by 2% each wave that has passed toward the last wave. regardless of the presence of the enemy from the entrance or not. The maximum damage from each enemy is 3x as much as their original damage.
All artilleries hit the ground at the same time, regardless of the distance of the target.
Allies always hit before enemies, while enemies always use ranged attack before allies.

The amount of time it takes the Rain of Fire to hit the surface is 1.0 second.
The amount of time it takes the Thunderbolt to hit the surface is 0.5 seconds.
The amount of time it takes the Soul of Impact to hit the surface is 0 seconds (instantly), however the damage is first dealt after a slight delay.

Types of Enemies	Formula
Armored	(100-x)% × physical damage
Magic Resistant	(100-x)% × magical damage
Artillery explosion to armored enemies	(100-x/2)% × damage
Artillery damage to enemies with physical damage immunity in KRV	50% × damage
Artillery explosion	highest damage (center of explosion) × 0.988^x, where x denotes number of pixels away from the center.
Health increment as each wave passed since the spawn in the endless levels	x(1.02)^y, where x denotes the initial health and y denotes how many waves has passed since the spawn.

Slot Number	Damage	Slot Number	Damage	Slot Number	Damage
Damage with Empowered Magic
1	10-19	18	18-28	35	27-36
2	10-20	19	19-28	36	27-37
3	11-20	20	19-29	37	28-37
4	11-21	21	20-29	38	28-38
5	12-22	22	20-30	39	29-38
6	13-22	23	21-30	40	29-39
7	13-23	24	21-31	41	30-39
8	14-23	25	22-32	42	30-40
9	14-24	26	23-32	43	31-40
10	15-24	27	23-33	44	31-41
11	15-25	28	24-34	45	32-41
12	16-25	29	24-33	46	32-42
13	16-26	30	25-34	47	33-42
14	17-26	31	25-35	48	33-43
15	17-27	32	26-35	49	34-43
16	18-27	33	26-36	50
17	18-27	34	27-36	51