Is the new thornmail even worth buying?

{quoted}

That's not how it works though.

It doesn't return more % of damage with more armor.

It returns 15% of damage and deals additional damage equal to 25% of bonus armor.

So, if you have 100 bonus armor (which is the least possible value, if you have Thornmail) then you will deal

25 magic damage + 15% of damage returned as magic damage.

Now, this means that new Thornmail (with 100 bonus armor) will be better than old Thornmail when the attacker deals 170 or less damage with autoattacks (which includes mages and some tanks).

However, if you want to outdamage old Thornmail on an ADC with... Let's say 300 AD then you will need:

180 bonus armor for every regular hit 360 bonus armor for every critical hit 450 bonus armor for every critical hit with IE

So yes, it's generally worse against actual ADCs in late game.

yup you are right... just test it last night... i forget to edit my posts...

if you buy all armor/health (dm plate, ro, ohm, sunfire cape, thormail for 12950 gold) on garen with no rune and masteries because bonus armor would be complex to calculate

max passive: 30 item: 305

83.75 so round to 84 magic dmg + 15% of AA (ignore 45 dps from sunfire cape passive)

lets say adc will dmg you

aa = enemy auto attack old = plain old fashion thormail which cost you 2100 ( old) new = thormail with lots of armor item which costs you 12950 (new prices calculated)

aa vs old vs new 250 vs 75 vs 121.5 (37.5 + 84) 500 vs 150 vs 159 (75 + 84) 750 vs 225 vs 197 (113 + 84) 1k vs 300 vs 234 (150 + 84)

and dont forget if adc or champion bought MR item so thormail reflected would be lower ...

what the result said... strong against weak AA... weak against strong AA... not effective cost anymore....

thormail might be good on champion with bonus armor such as malphite, rammus, garen, etc but sunfire cape is better item to give some armor, health and 25+lvl magic.... and thormail is not good first item tho...