That really surprises me. Armor/Magic Resistance is directly countered by Armor and Magic Penetration, but True Damage currently has no significant other if you catch my drift. Why not have Damage Reduction count to this? Yeah it's a tad rare on champs, but it would solidify characters like Alistar and Braum's place as defenders.
Edit: figured I'd add the link, http://leagueoflegends.wikia.com/wiki/True_damage
Also, unaffected by 
?
alfavhunter4 votesShields is the counter to % hp true damage
More hp or shields is the counter to true damage
Mind you some of the %hp true damage is completely out of hand at the moment
Asayake 5150glow3 votesTrue damage isn't supposed to have a counter, lol.
SettDownShutUp1 votesI guess, but maybe the question I'm asking is, should it? If people are so vehement about it that the very mention of "Guillotine" sent threads on threads of hate, maybe instead of nerfing the True Damage like everyone is begging with Vayne atm, there could be an option the player can take themselves.
Asayake 5150glow2 votesI guess, but maybe the question I'm asking is, should it? If people are so vehement about it that the very mention of "Guillotine" sent threads on threads of hate, maybe instead of nerfing the True Damage like everyone is begging with Vayne atm, there could be an option the player can take themselves.
The funny thing is, people complained about Vayne's true %health damage, right? In this update, her %damage was buffed, and the bases removed. And it's still true damage.
Also upvoted this to make it not negative, not sure why people would downvote it.
Anyway - The item would be a little too specialized (I guess), because you would almost always take it (because no matter how far behind the one with true damage is, they'd still do plenty of damage to you). But then, it's pretty much the same way when you face a Yas - always take a Randuins.
And the real counter to Vayne? FM + Randuins. The AS slow is heartbreaking (played as Aatrox against someone who stacked these, I was rekt...)
Bârd1 votesThink of it this way: Armor grants % reduction against physical damage MR grants % reduction against magic damage DR (depending on the source) grants flat or % against one or both of those.
True damage bypasses all forms of damage reduction, so none of those have any effect.
However, there are still ways you can increase the number of hits you can take
Against Flat true damage 
, you can stack health to increase your durability (though their true damage is the minority of their damage, so you should itemize against their other abilities)
Against % true damage 
, you need to increase your EFFECTIVE health while not increasing your maximum health. This can be achieved in two ways: Heals and shields.
On a side note, 
ult can negate true damage.
DarkRitual1 votesThe counter to true damage is Health.