Been using her a little bit in an Ally heavy Mono Spirit Deck, and she can be a beast at the right time. The deck is on cardgamdb, the first Caldara deck posted(I did not make it, but did tweak a bit.)
Just played Road to Rivendell, Sleeping Sentry killed 2 Ethir Swordsman and a Shipwright. Next turn I threw her away to bring those 3 back for free, which amounted to 8 WP per turn. Losing the resource kinda sucks, but depending on what time you use her ability, 100% worth it. She also has solid synergy with Emery.
Enjoy that the designers are coming out with interesting strategies.