The new duskblade is NOT good on Vayne
Vayne needs to continuously auto attack to deal dps and you have to stop AA'ing to get the duskblade damage. She needs to stay in stealth for one second if she wants to repetitively use the duskblade, thus losing more DPS and gaining. If you guys really want to cry "duskblade op" do it for kha'zix. That shit is literally kha'zix's wet dream.

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or
or just any item that gives you either sustain or raw damage to reinforce your Q burst.