"Did I not just throw a knife?" The illusion laughed. Loki made sure to maintain the edge of breathlessness to it that would sell having just had the air knocked out of him. Valkyrie clearly knew something was off, but not what. And that was magnificent. Most people, even Thor sometimes, fell for the illusory replacement hook, line, and sinker. Loki had sent many an enemy off a cliff or arranged a convenient backstab hundreds of times via convenient duplicate, he'd tricked people into letting him out of rooms they thought he'd already escaped. Almost no one saw through it, even partially, the first time.

A little more verisimilitude was called for. Loki telekinetically pulled the knife he'd thrown out of the boxelder and sent it back to the illusion, who 'caught' it handily. (In reality, of course, Loki never released his mind's control over the blade.) "Perhaps I'm waiting for your follow-up. You throw me against a tree and then decline to press your advantage? That seems odd."

While the illusion spoke and 'held' the knife - its undeniable reality hopefully 'proving' the illusion's reality - the actual Loki moved silently around to put himself behind Valkyrie.