Cost increased. Attack damage and armor penetration increased.
Making Last Whisper more effective as a component item while building into Lord Dominik's Regards or Mortal Reminder.
COST :  ⇒ 1450 gold
ATTACK DAMAGE :  ⇒ 20
ARMOR PENETRATION : [10%] ⇒ 20% total armor penetration
Bonus armor penetration shifted to total armor penetration (and decreased).
The problem with an armor penetration item that only feels good against armor stackers is that most champs don't feel good about getting it early to ensure their damage stays relevant as enemies build armor (they want to be killing squishy targets instead). But once tanks really armor up, damage dealers feel bad if they didn't purchase Last Whisper earlier. We're moving Last Whisper into a middle ground so it'll still scale against tanks but feel like less of a dead-end against other squishies.
ARMOR PENETRATION : [35%
bonus] ⇒ 10% total armor
ARMOR PENETRATION : [45% bonus armor] ⇒ 35% bonus armor
Armor penetration up, attack damage down.
For marksmen, reacting to tanky threats required a 2700-gold investment in the form of Lord Dominik’s Regards or Mortal Reminder. The problem: “build an end-game item” doesn’t pass muster as a ‘reaction’, given how long it takes to bank that much coin. We’re letting Last Whisper serve as that reactive purchase all on its own, at the expense of effectiveness against targets without armor to pierce.
BUILD PATH : [Pickaxe + 425 gold (1300 total)] ⇒ Long Sword + 950 gold (1300 total)
BONUS ARMOR PENETRATION : [30%] ⇒ 45%
ATTACK DAMAGE :  ⇒ 10
Simply put, the answer of when to buy Last Whisper previously was 'pretty much always'. While certainly better when the enemy was armor-stacking, the total armor penetration meant it was always a sizeable and necessary damage increase in any situation. Last Whisper now occupies a reactive slot, letting you forego it when the enemy's just as reckless as you are.
TOTAL cost : [2300 gold] ⇒ 1300 gold
BUILD path : Pickaxe + 425 gold
ATTACK damage :  ⇒ 25
armor penetration : [35% total armor penetration] ⇒ 30% bonus armor penetration
- Combine cost increased to 1,025 from 860 (total cost is now 2,300 from 2,135)
- Last Whisper's Armor Penetration reduced to 35% from 40%
- Will now show up as a Pickaxe upgrade in the item shop
- Cost increased to 2,290 from 2,090
- Recipe changed to Pickaxe and Long Sword
- Upgrade cost increased to 700 from 500
- Now provides +40 attack damage and 40% armor penetration
- Unique armor penetration now functions with abilities (but still not against turrets)
- Bonus damage decreased to 10 from 20
- No longer works on turrets
June 19, 2009 Patch
- Armor penetration changed from 33% to 40%
May 23, 2009 Patch REMAKE
- Now penetrates 33% of the defender's armor (unique)
- Reduced recipe cost from 850 to 750
May 9, 2009 Patch
- Bug fixed which gave it an ability power ratio of 1.0
May 1, 2009 Patch
- Functionality changed from "50% chance to ignore all of the target's armor" to "35% chance on hit to deal 1 magic damage for each point of armor the target has."
- Increased recipe cost from 600 to 750