If the enchanted creature is no longer on the battlefield when Penumbra Umbra's second ability resolves, use its copiable values as it last existed on the battlefield
You can cast them more efficiently than other spells of its type, and get to the ability that comes with it faster
But it's also true that people can use Encroaching Mycosynth to make the battle an artifact, then The Blackstaff of Waterdeep to make it a creature, then Arcane Adaptation to make it a Human, then Moonmist to transform it, and because of the changes to DFC token rules introduced for Incubator tokens, that token would then transform
Except instead of people, we'll be drafting Magic cards
All creature spells you cast have Offspring Two
Core Lineup for a Bamboo Sword Engine: 3| Fiendish Bamboo Sword 3| Golden Bamboo Sword 2/3| Soul Devouring Bamboo Sword* 1/2| Broken Bamboo Sword* *The typical balance is 1 Broken and 2 Soul Devouring, but if you are running monsters that may attack directly, maximizing the draw phase lock may be preferable