When playing imbue druid with hamuul, if you change your hero-power using a hero card, you will be unable get your imbued hero-power back regardless of whether you play 2 spells nor play an imbue card (such as Flutterwing Guardian).
Here’s the scenario that made me aware of this:
I’m playing Hamuul Druid against a Death Knight. I imbue 4 times through playing spells. I play Malorne and get Ashamane. I play Ashamane and get the Headless Horseman Hero Card. I play the Headless Horseman Hero Card. My hero power is now ‘pulsing pumpkins’. I play 2 spells → my hero-power is still ‘pulsing pumpkins’. I play Flutterwing Guardian → my hero-power is still ‘pulsing pumpkins’.
How I know this is a bug:
Mage can imbue their hero-power, then play Artanis (changing their hero-power), then play Flutterwing Guardian and their hero-power will reimbue into ‘blessing of the whisp’.
Potentially Useful Info:
I am using the druid tourist that allows me to play mage cards.