How does defend work?

How does the skill defend work? Is it a trigger heal kind of like the Bristle Back hero in dota or is it something else entirely? Shoot I have to stop assuming everyone plays the greatest game in the world. The hero Bristle Back has a passive ability that reduces damage. How it works is it takes the incoming damage and instantly heals it back to the hero. If it works this way armor stacking and defend will stack alright. If it doesnt defends damage reduction + the damage reduction recived from armor items will not be very high. If you have aleady high damage reduction the most defend will add is another 5-8% tops.

i think glorn said before damage reduction doesnt stack

Um yes it does. Damage Reduction stacks with dimishingly returns. Damage Block doesnt stack theres a big difference. Now here is what confuses everyone on even me a little Damage Reduction stacks with dimished returns but armor stacks fully. Every point of armor adds about 6% of your maximum hit points to your EHP or the amount of damage needed to kill you. Armor and Damage Reduction are completly independent of each other. Check out some answers I found some guys guide on it he even proves it with mathcraft and everything.

yeah, damage reduction (reduces damage by 200) stacks with deminishing returns, but not with itself. the question is, does say, 90% reduced damage (from armor) stack with 65% reduced damage of defend?

late game, fighting rag, there is a noticable difference between having defend on and off, but that doesnt help answer anything as far as math craft goes.

end game, an extra 5-8% damage reduction is a lot though, every 1% is a lot once you beak 90% and have an item evasion. 5% of 1000 damage is still 50 damage reduced per hit. very late game, most players have 3000 damage, and attack 2 times per second. every second of fighting, you are saving yourself 300 HP with an extra 5% damage reduction. in a duel that lasts 1 minute, that is 18000 HP. (some mathcraft for you)

It is a lot assuming damage reduction works like spell reduction I will use neura's math formula. The highest damage reduction I have ever reached in a game is 95% and that was with Immortals Sheild, Mask, and Armor.

(1 - (1 - .95) * (1 - .65)) * 100
(1 - (.05) * (.35)) *100
(1 - (.0175)) * 100
(.98) * 100= 98% Damage Reduction
The absolute least amount of damage reduction Defend adds is 3% but come on if you have all those items you already won and dont care.

Realistic if you went something like Sheild you will have about 88% Damage Reduction

(1 - (1 - .85) * (1 - .65)) * 100
(1 - (.15) * (.35)) * 100
(1 - (.0525)) *100
(.95) * 100 = 95%
so in most cases it will add 7% Damage Reduction.

Something I have wondered (for my self) Using Ring of Masterful Sheilding Alone

(1 - (1 - .60) * (1 -.65)) *100
(1 - (.40) * (.35) *100
(1 - (.14))*100
(.86) * 100= 86%
So this would add about 26% Damage Reduction maybe one of the best builds you can do with this skill would be Ring of Masterful Sheilding and Rushed Immortals Boots. Or well for an intelligence hero Shroud of the theif god and Immortals Boots.