What was the warden mail?

Warden's Mail is very useful early in the game against autoattackers. For skirmishes while laning, its armor provides good survivability and its attack speed slow is valuable, especially against champions that rely on their autoattacks to deal damage

UNIQUE Passive - Cold Steel: If you are hit by a basic attack, you slow the attacker's Attack Speed by 15% for 1 seconds.

V3.10:

Passive slow duration reduced to 1 second from 1.5.
Cost reduced to 1000 from 1100.

League Of Legends Items Details : elohell.net