It happened faster than Kir could process.
One moment, he was falling backward, the mimic's core in his arms, and the next, his clothes flew off and Mimzy pulled her entire bulk from his dimensional storage, washing over him as she dove for the mass of dying mimic spreading herself into its bulk as she began to consume it.
She's gotten much bigger than I thought... Kir thought, realizing that the sheer amount of Mimzy on display should not have fit into his dimensional storage, and her implied weight should have left him completely drained of magic... How did she get so massive?
Kir had trained Mimzy by feeding her magic pulses to produce his clothes, feeding her magical garments that she could reproduce far better than regular ones.
Unheeding of his thoughts, Mimzy left Kir completely naked as she finished leaving to consume her parent.