What "True" Stuff do we have?
So we've got True Damage, True Stealth (Obscured), True Ice.
Anything else?
So we've got True Damage, True Stealth (Obscured), True Ice.
Anything else?
True Sight
Soon there's gonna be "true movement speed" and "true crits", believe me in the next few seasons there's gonna be so much "true" bullshit like "true terrain", "true cooldowns" and sooner or later there's gonna be "true ping" and "true fps"
Truely Outrageous 
True cancer 
True Bear 
Damage reduction reduces all sources of damage except True Damage.
Invulnerability makes you immune to all (common) sources of damage, even True Damage.
So technically, all invulnerability spells are 100% True Damage Reduction.
Fun side note: There actually exists a fourth type of damage known as "Pure Damage".
Pure Damage is only dealt by two sources in the game, the Nexus Obelisk and Sion's Glory In Death self-damage.
Pure Damage is a lot like True Damage, but the defining thing about it, is that it ignores aforementioned invulnerability spells.
I dread the day CertainlyT (d)evolves into CertainlyP.