2 items: When you cast Whirlwind while in combat, you gain a stack of Chaotic Whirlwind for 5 seconds, granting you 5% Movement Speed per stack, up to a maximum of 5 times. While Chaotic Whirlwind is active, you gain 6 Damage for every 1% bonus Movement Speed you have, up to a maximum of 450.
At 5 stacks, the duration doubles but cannot be refreshed.