I'm building armor yet she goes through my health in 0.5sec, almost the same case as lee sin when you build armor but still dies in 1 shot. Is there a Secret or a bug to her damage? is 3k hp and 150 mr not enough to survive her burst? Last I checked her AP base damage and ratio aren't that hard. You get 100 MR and you survive Leblanc burst, but you get 150 Mr you still die to diana.
Marshbouy3 votesIt's because the Diana built 6 wits ends and shredded all of that MR you built
Radiant Wukong2 votesDiana = DPS fighter LeBlanc = Burst assassin
I'm pretty sure you're surviving Diana's first rotation.
Tahminatrix 1 votesIt depends on diana`s build, the most prevalent is going full ap / magic pen and oneshotting someone in a single rotation.
Radiant Wukong1 votes[{quoted}](name=Radiant Wukong,realm=NA,application-id=3ErqAdtq,discussion-id=NvJjrUoG,comment-id=0001,timestamp=2018-11-19T02:26:04.676+0000)
Diana = DPS fighter LeBlanc = Burst assassin
I'm pretty sure you're surviving Diana's first rotation.
I've never seen that build. I always see 
iiGazeii1 votes100 MR reduces incoming magic damage by 50%. 150 MR reduces it by 60%. Once you've built 100 MR, it's more valuable to build health than more MR.
Diana also often runs Sudden Impact, Sorc Shoes, and Void Staff, which give her a ton of magic penetration.
DuskDaUmbreon2 votesThat's not quite how MR works.
1 point of MR is basically an extra 1% of your max health versus magic damage.
Yes, the reduction isn't as great, but when you set it up on a graph with a comparison of effective reduction it's linear in effectiveness.
...Basically each point of MR or armor is just as effective as the last point was, however there is still a point where building more health would be more cost effective.
EDIT: I should have mentioned that the other part of what you said is pretty accurate. She builds a lot of pen, but she also has a solid amount of DPS.
iiGazeii1 votesEach point is just as effective as the last, but you still get diminishing returns because that 1% of your maximum health doesn't change.
For math's sake, say you have 1000 HP. If you build 50 magic resist, you get 50% more effective HP, so an extra 500 effective HP. If you build another 50 magic resist, you get another 500 effective health, but 500 isn't 50% of your new effective health total of 1500. It's only 33% of your effective health. That's the diminishing returns.
Since magic resist is a percentage of your base health, the more you build, the more valuable building health becomes, and vice versa. If you want to have the most effective health possible, you need to build a mixture of health and armor/MR, not just one or the other.
Illabethe1 votesI'll give you an honest answer: It's because Mechanically, if Diana HITS you, she probably hits you with every single part of her kit. It's unavoidable once she hits a Q and is range.
What I mean is:
She hits you with all 3 orbs from W on Ring in. She hits you with multiple R's after you are hit with Moonlight from Q. She hit you with Q.
Most champions give you a little lee-way if they miss a skill or two when built on hit, because some part of their kit is a skill shot or something. In Diana's case, the only part of her entire kit that isn't 100% guaranteed to hit, is her Q, and that's her initiator......
Ie...... most champs have the capacity to kill 50% Reduction champs TWICE in their damage output per kit. Diana's kit nearly guarantees it.
Ways around it:
-Move speed to avoid the Q's.
-Ways to heal mid combat, like 
's W
-Dashes/Flashes to avoid the spheres when she R's in, and hopefully get far enough away that her E can't pull you back in.
You can also get 
. Her kit relies on multiple hits from the same spells, so this is actually an extremely strong item versus her. W hits three times, and R can proc 2 times per moonlight. Adaptive significantly mitigates some of that.
There's also a very risky thing you can do while Diana is engaging: Her R is NOT a Blink. You can skill shot her with a hard CC and it will disrupt her R. After that, she's worthless for 4-5 seconds.
P.S. a Good Leblanc... you will not survive with 100 mag resist unless it's VERY early game lol.
Bloodnacht1 votesThere's also a very risky thing you can do while Diana is engaging: Her R is NOT a Blink. You can skill shot her with a hard CC and it will disrupt her R. After that, she's worthless for 4-5 seconds.
P.S. a Good Leblanc... you will not survive with 100 mag resist unless it's VERY early game lol.
Or play
and max W for cd and she's useless