I like the idea, but it is complicated. I would settle for an Changling ability that lets you gain an ability from any unit in your line of sight, maybe 1 discard for gaurds and 2 for mages. Then the discard cost of the ability, you gotta earn it!
Thats a nice unit, but it doesn't have the fun factor of the uncontrolable nature of absorbtion. Absorbtion alone would make it a fun unit, but then u'd completely loose control over ur own units status, therefore it needs transformation to give u back at least a little of it.